Let's say that an ancient race of beings locked away some sort of evil that could destroy the world if unleashed. Let's also say that unleashing it would be relatively easy to do if not warned of danger.

Using only Aztec or Ancient Egyptian level technology, how could the race warn the future not to mess with the evil being's prison in a way that would last an absurdly long time (let's say for simplicity it needs to survive 100,000 years) that can be easily comprehended by anything and anyone, considering how much language changes in only a few thousand years.

Note: The ancient race can work together on an Ancient Egyptian scale, but has no access to magic or modern technology.

Edit: Pardon the weird and contradictory circumstances in which they need to warn others, but the question is how to do so, not why they need to. Also, it's reasonable to say that people are curious and will eventually do what they're not supposed to, but that's irrelevant to what my problem is here.

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    $\begingroup$ Possible duplicate of How might modern humans leave a message for 50,000 years? $\endgroup$ – Mołot Feb 28 '18 at 8:37
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    $\begingroup$ The oldest message I'm aware of that's still meaningful comes from Australian Aboriginals about a sudden sea level rise some 14'000 years ago. All things considered, the message has survived quite well. $\endgroup$ – Samwise Feb 28 '18 at 21:52
  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – Monica Cellio Mar 4 '18 at 23:07
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    $\begingroup$ The supposed duplicate linked above specifies modern humans with modern technology, while this question requires Ancient Egyptian-equivalent technology (and, presumably, understanding of the world). I think the two scenarios are different enough to keep this question open. $\endgroup$ – rek Mar 8 '18 at 4:01

20 Answers 20


This problem has actually been considered very seriously by very serious people, in the context of warning future generations of the dangers associated with long-term repositories of nuclear waste.

  • The Human Interference Task Force was "a team of engineers, anthropologists, nuclear physicists, behavioral scientists and others [...] convened on behalf of the U.S. Department of Energy and Bechtel Corp [with] [t]he goal [...] to find a way to reduce the likelihood of future humans unintentionally intruding on radioactive waste isolation systems".

  • One of the best documents in the "Expert Judgment on Markers to Deter Inadvertent Human Intrusion into the Waste Isolation Pilot Plant", Sandia Report SAND92-1382 (1993), Kathleen M. Trauth, Stephen C. Hera, Robert V. Guzowsti, eds.

    Expert elicitation was used to determine the potential for markers to deter inadvertent human intrusion by future generations into the Waste Isolation Pilot Plant (WIPP). Specific goals were to obtain information about marker designs and message formats that will remain in existence and interpretable for the required time period of regulatory concern, and to estimate the effectiveness of specific marker designs in deterring intrusion and communicating a warning to future generations about the location and nature of the waste buried at the WIPP. The assumption was made that when individuals know what materials are buried in the area and the dangers of intruding into the material, they will not do so.

  • There is an excellent bibliography with on-line links titled "Preservation of Records, Knowledge and Memory Across Generations" and prepared by the Nuclear Energy Agency Radioactive Waste Management Committee of the OECD.

  • You may want to watch the excellent documentary Onkalo into Eternity about the design and building of the Finnish Onkalo spent nuclear fuel repository. (And high-definition version, unfortunately with hardcoded Romanian subtitles.)

Sandia National Laboratories' "Expert Judgment on Markers to Deter Inadvertent Human Intrusion into the Waste Isolation Pilot Plant" contains two appendices, Appendix F and Appendix G, describing the markings proposed by two different teams of experts labelled "Team A" and "Team B".

  • Team A, led by Kathleen M. Trauth, found that

    [The] basic principles to guide current and future marker development efforts [are]: (1) the site must be marked, (2) message(s) must be truthful and informative, (3) multiple components within a marker system, (4) multiple means of communication (e.g., language, pictographs, scientific diagrams), (5) multiple levels of complexitiy within individual messages on individual marker system elements, (6) use of materials with little recycle value, and (7) international effort to maintain knowledge of the locations and contents of nuclear waste repositories.

    The efficacy of the markers in deterring inadvertent human intrusion was estimated to decrease with time, with the probability function varying with the mode of intrusion (who is intruding and for what purpose) and the level of technological development of the society.

    Their idea was to use massive earthworks to convey the importance of the site, and multi-language durable inscriptions to convey the actual message:

    The central area of interest is surrounded by earthen berms. For the WIPP site, the area of interest is where we do not want drilling or excavation to occur. In the design the central area is the area of the underground panels plus either (1) a one-fourth-mile buffer zone, or (2) the distance to which the radionuclides may migrate during the 10,000-year period, whichever is larger. The forms of the earthworks are jagged and rough, suggestive of energy radiating from the central area. The berms serve several purposes. First, they define the area of interest. Their size is set so that sand dunes are unlikely to cover all of them entirely at the same time. Instead, the wind will leave dunes streaming behind the berms and create an even larger marker.

    Second, their shape sets the tone for the entire landscape -- non-natural, ominous, and repulsive.

    Third, the corner berms are higher than the others and provide vantage points for viewing the entire site.

    Fourth, the comer berms also include buried rooms with all the message levels recommended for inclusion in this marker system. As the berms erode, these rooms will become uncovered at various times. The investigator will be guided toward the center of the site by the berms. Prior to entering the central area, however, he or she will encounter a “message kiosk”. Each message kiosk is composed of a message wall and a protecting wall. In terms of site layout, the message kiosks form the only “nurturing” part of the marking system design. The protecting wall is of concrete and is meant to protect the message wall from erosion. The message wall is of granite or other hard rock and is a vertical, curved form. There are two reasons for a curved form: (1) it makes it very difficult to reuse the piece for another purpose, and (2) it is not an honorific form such as an obelisk. The vertical aspect minimizes tensile stress on the components.

    To solve the problem of the perishability of language, Team A came with an ingenious solution: the multilanguage inscription is to contain blank spaces where future generations should inscribe the same message in their language; and in the text of the message is to be written: "If the marker is difficult to read, add new markers in longer-lasting materials in languages that you speak".

  • Team B, lead by David B. Givens, came with two interesting opinions; first, the scale of the marking system should be kept with human grasp, and, second, there should be a uniform international system of marking, in order to increase the chances of correct understanding.

    Specifically, they proposed:

    • (A) Berms or earthworks to help define the perimeter of the surface area directly above the waste repository. The earthwork might be arranged in the shape of a symbol, yet to be determined.

    • (B) A ring of granite monoliths, around or within the perimeter of the marked area, bearing a variety of symbolic, pictographic and linguistic inscriptions.

    • (C) A central granite structure to house more detailed textual, narrative, diagrammatic and scientific information.

    • (D) A large number of small, durable markers inscribed with basic warning information, seeded at various depths within the marked area and in the surrounding earthworks.

    • (E) Buried duplicates of the granite monoliths placed in key locations at various depths, such as in the plugs of sealed airshafts.

    • (F) A layer of contrasting dielectric materials at the surface to permit remote detection by radar (perhaps arranged in the shape of the designated marking symbol).

    • (G) Duplicates of markers placed in Carlsbad Caverns and in off-site archives.

    They even proposed the inclusion of a system of pictographic definition of conventional symbols, to increase the chances of understanding by future archaeologists.

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    $\begingroup$ if you added one or two of their best ideas this would be a way better answer, as it sits this is basically a link answer. $\endgroup$ – John Feb 28 '18 at 2:07
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    $\begingroup$ Berms, monoliths and buried markers sound a lot like the archeological sites that we keep digging up. E.g. Stonehenge. $\endgroup$ – Bald Bear Feb 28 '18 at 5:25
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    $\begingroup$ Strange, I'm sure I have read about the very same project on this site already. Sure this question is not a duplicate? $\endgroup$ – Mołot Feb 28 '18 at 7:16
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    $\begingroup$ 'The assumption was made that when individuals know what materials are buried in the area and the dangers of intruding into the material, they will not do so.' Perhaps an unfounded assumption. $\endgroup$ – Justin Thyme Feb 28 '18 at 14:12
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    $\begingroup$ "The ancients made these huge structures and left all those pictograms in their incomprehensible language, there must be a great king buried here with huge treasure..." Seriously this will probably work fine as long as people refresh the markers to keep them comprehensible but after that more effort just suggests greater value. That said, that is not the fault of the answer, obviously. $\endgroup$ – Ville Niemi Feb 28 '18 at 23:06

Where have I heard this before ?

Sounds something like the plot of practically all the Indiana Jones movies, not to mention The Fifth Element and, well, lots more.

I doubt this is possible.

Using only Aztec or Ancient Egyptian level technology, how could the race warn the future not to mess with the evil being's prison in a way that would last an absurdly long time (let's say for simplicity it needs to survive 100,000 years) that can be easily comprehended by anything and anyone, considering how much language changes in only a few thousand years.

The first problem is that an race with that level of technology would have no way of knowing how long a material or structure would survive. Even the concept of wear and tear, weathering and corrosion over such large time scales would be beyond their ability to estimate. It's doubtful the concept of a time scale that long would meaningful to them.

It's doubtful we could make a structure that would last that long.

To put this in perspective, the oldest known structure is about 7000 years old (less than a tenth of your goal). It's worth reading it's history under modern man to get a feel for what happens old structures.


Making this even more challenging is that over the course of such a long time scale, geography changes in quite considerable ways. The best example is Doggerland.

Until about several thousand years ago there was no North Sea and you could walk to France from the UK !

This is the kind of change that can happen in thousands of years, and the kind of changes your builders would have no comprehension of. Anything they build could be made a mockery of by geology and time.

Some psychology.

Take a container about the size of a biscuit tin. Bring it to work and put a large sign on it saying "do not open - deadly snake inside". How long do you think it would be before someone decided they had to know if there really was a deadly snake inside and that opening it was the best way to find out ?

People are curious and telling them they can't open something to see for themselves is just asking for trouble.

Now let's apply this to your mysterious prison. Over the course of 100,000 years it is inconceivable that no matter what you say about what's inside, someone won't open it up. And that's assuming they actually understand your warnings.

And that's not new. The people in your story planning to build this would know that as well - it would be a fact in their day as much as in ours.

So ...

Let's say that an ancient race of beings locked away some sort of evil that could destroy the world if unleashed. Let's also say that unleashing it would be relatively easy to do if not warned of danger.

So whatever you do you need pictures. Rock, to anyone of that time, lasts longest and they'd use the hardest rock they could. They use redundant messages, repeats in all the languages they knew and all the painting they could.

When I say rock, I means lots of rock. Mountains of rock. Covered in more rock. With clay and earth and sand and lots more rock.

And they'd create a group that was dedicated to passing the knowledge down from generation to generation.

And, like all who tried that before them, it would get muddled and fail. The stories would become myth and legend in time. Few would believe them and those that did would be considered a bit whacko - the tin foil hat brigade.

But if someone did believe these horror stories, there's one last bit f psychology to consider :

Some idiot would actually want to unleash the horror.

So, even if they succeeded in warning people, over the course of 100,000 years some group is going to open it either due to curiosity, stupidity or because they want to see the world burn.

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    $\begingroup$ the best example is the death threats we've been ignoring all our lives written on egyptian tombs if someone were to break the seals. $\endgroup$ – CptEric Feb 28 '18 at 14:30
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    $\begingroup$ Personally it's those Microsoft EULAs that you have to accept before opening the packet - those things could mean anything and yet we all ignore them ! :-) $\endgroup$ – StephenG Feb 28 '18 at 14:38
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    $\begingroup$ How long do you think the container would stay closed if instead the sign said "Do not open - raw sewage"? Don't try to convince people the contents are dangerous, convince them the contents are repulsive. $\endgroup$ – Mark Mar 2 '18 at 1:02
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    $\begingroup$ @Mark "trash archaeology". Digging in old trash heaps is how we learn about the past, and it's how our descendants will learn about us. Some intrepid researcher will think he can extract our DNA from poop. $\endgroup$ – RonJohn Mar 2 '18 at 1:46
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    $\begingroup$ @StephenG Legally speaking it's fairly safe to ignore EULAs; Unreasonable terms are invalid anyway. $\endgroup$ – Cubic Mar 2 '18 at 11:46

Genghis Khan's tomb has not been found. He requested that, so they made a deep hole, placed him in then put back the ground, didn't put any sign and story says that they went with their horses in every direction, trampled earth both while going to the dig site and after finishing the burial going away. And did that so randomly that after time passed it was impossible to trace them back.

If you want to keep something hidden, don't put signs saying "don't open this", put it somewhere no one can find it.

It is generally a Hollywood go to stupid plot this thing of "warnings from the ancients". When people want to hide something or keep it away, they do just that, they don't make it easy to find and then write "don't look inside".

So my question is: is it so important for your plot to have them write something there and so perpetuate a stupid stereotype or you can concentrate your story on the actual building of the tomb and on its secrecy? Because if you don't concentrate on writing useless stuff, you can make it simple by creating a stone prison and then bringing mud and dirt and planting trees and so creating a "natural" looking hill. Like the Chinese did with their pyramids, but in your case it would be an intentionally forgotten, never spoken about place. And the release of this ancient evil can be done by accident (your present time civilization can dig a tunnel there for a highway or whatever).

  • $\begingroup$ That could be a good way to leave this thing forgotten for many years. But there could be potential issues to just burying it underground. Something very powerful and evil could perhaps telepathically speak to passersby, potentially kill off all plant life around its site (making the burial position obvious), etc, etc... But we are missing details from the OP to truly know these things. $\endgroup$ – Tyler Dahle Feb 28 '18 at 16:42
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    $\begingroup$ I agree in principle with your comment, but if that is the case he can add complexity to the burial site and thus leave clues for the heroes who try to stop the ancient evil. So lets say that mercury can stop the telepathy powers and the destruction of plants is a form a radioactive power the evil has. So the tomb has rocks carved, then enveloped in lead, mercury and enveloped again in lead and outside it all an entire new level of rocks. and the lead/mercury width is not huge as to be obvious during the digging with the automated machine. $\endgroup$ – Andrei Ioan Danaila Feb 28 '18 at 16:53
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    $\begingroup$ And then the heroes investigate and find a way to trap the evil again. This way he can build more on the characters, on their ingenuity and rely less on "the ancients told us" overused plot. $\endgroup$ – Andrei Ioan Danaila Feb 28 '18 at 16:54
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    $\begingroup$ This is a better option if you get to choose where to lock up the evil. If you don't get to choose, you could happen to lock up the evil in a place that is naturally attractive to civilization or rich with valuable resources, so it's going to get dug up sooner rather than later if there is no warning. $\endgroup$ – JPhi1618 Mar 1 '18 at 21:25
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    $\begingroup$ I think this answer only works assuming "short" time spans of a few millennia or so. If the society trying to do the warning is concerned about keeping the evil for absolutely as long as possible, out to tens of thousands of years, then they simply can't ignore the possibility of it being randomly found, no matter how well hidden. $\endgroup$ – Harabeck Mar 2 '18 at 22:32

Use Drawings instead of Language

The oldest drawings found are from 35000-40000 years ago.

Drawings are universal. They transcend language. Even when language change, drawings and imagery doesn't.

You can draw the prison. You can draw the evil beings. You can draw the consequences of opening up a prison. You can even draw starcharts to indicate years/time passing.

  • $\begingroup$ The simplest and best answer. As the answer points out - we've done this, and this is the method! $\endgroup$ – Fattie Feb 28 '18 at 11:48
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    $\begingroup$ “Drawings are universal. They transcend language.” — nohooo. Pray, how do you draw “the evil beings”, conveying their evilness, without resorting to shared cultural context? $\endgroup$ – Konrad Rudolph Feb 28 '18 at 18:28
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    $\begingroup$ I've attempted to use software designed by people who thought "drawings are universal". Key word: attempted. Even being an expert in the prior edition of the software wasn't enough to make it usable. $\endgroup$ – Mark Mar 2 '18 at 1:04
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    $\begingroup$ How do you draw "go away"? (It was a real learning experience when my Italian tour guide kept waving good bye but telling me to not walk away: what Americans think is a wave good bye is the Italian gesture for "come here".) $\endgroup$ – RonJohn Mar 2 '18 at 1:48

Keep the knowledge alive.

Aboriginal Australians have traditions that correctly mark sites that haven't been above the ocean for ten thousand years. Some of their religious sites have evidence 40,000 years old.

But that's not enough.

A lot of the reason they have been able to do this is because no one else really bothered them for a long long long time. Once outside people started coming it didn't work out as well.

Most famously a big red rock in the middle of a huge desert featured in lots of postcards isn't supposed to be climbed, taking a piece of it carries a curse and even photographing some parts is forbidden, but more than 100000 people climbed it last year and the Australia postal system continually receives souvenir pebbles from visitors hoping to uncurse themselves.

You need to keep the religion powerful.

A major religion has more than a 1000 year tradition of being at least locally powerful, of keeping exact traditions including reciting the main text in its entirety, and giving high importance to a particular place and objects. Exactly why it has been able to do this is harder to say.

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    $\begingroup$ Keeping the knowledge within the context of a religious is asking for it to be mocked by newer religions, agnostics and atheists a few millenia later. $\endgroup$ – The Square-Cube Law Feb 28 '18 at 12:10
  • $\begingroup$ Is mocking meaningful? $\endgroup$ – user25818 Feb 28 '18 at 16:53
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    $\begingroup$ Suppose, for an instant, that christians were right and eating meat on Friday could cause the end of the world. Now listen to Tom's Lehrer intro speech to "The Vatican Rag". $\endgroup$ – The Square-Cube Law Feb 28 '18 at 18:24
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    $\begingroup$ I'm not sure I've heard the story that eating meat on meatless days ends the world, just makes your afterlife unpleasant. But the point I was trying to make with the last part is that keeping temporal power is an important consideration. I don't care what some singer on a different continent says so long as at least one key component is safe in my holy city/mountain/fortress/whatever. How many cartoons will it take for Islam to abandon Mecca? But the Next Dalai Lama officially needs permission from Beijing to be born. $\endgroup$ – user25818 Feb 28 '18 at 18:50
  • $\begingroup$ @notstoreboughtdirt "Is mocking meaningful?" yes, because people (especially young ones) don't like to be mocked, especially when your only response is, "yeah, well, the Pope says so!!" $\endgroup$ – RonJohn Mar 2 '18 at 1:52

Many answers have discussed ways to keep people out by combinations of persuasion, force, and hiding.  I had less well developed versions of a couple of these ideas (e.g., pictographs — see also my comment here), but here’s one that that I didn’t notice in any previous answer (sorry if it’s there and I skimmed past it):

Obviously, beyond a certain point, you want to make the area hard to enter, to protect against people getting too close by accident.  (Other answers have suggested having a large surrounding buffer zone that is hard to damage but easy to enter, and using it as a repository for information and warnings about the danger.)  But, starting at or beyond the inner perimeter, where you don’t want people to enter, make it obviously hard to leave.  Make it look less and less like a fortress or a bank vault, that might be guarding something valuable against intruders, and more and more like a prison that’s keeping something in (and protecting the outside world from the prisoner).  Some specific ideas:

  • Have the “prison” area at a lower level than the surrounding ground (i.e., in a pit) with smooth, vertical walls.  This concept has been used for many years to contain bears and big cats in open-air enclosures in zoos.  This is what such an enclosure looks like under construction / maintenance:

    [Click to see larger image]

    This is what it looks like in normal use:

    [Source]  [Source]

    And this is what happens when it’s built to inadequate specifications:


  • Have doors that are apparently locked from the outside, like

    [Source]  and [Source]

    Transparent doors will let people see that the locking mechanisms are primarily designed to prevent the door from being opened from the inside.  It’s OK if these doors are, in fact, also hard to open from the outside; e.g., with locks holding the locking bars in place.

  • Have weapons aimed toward the inside.  Based on the constraints of the question, these would probably have to be passive defensive weapons (unless you believe that the Indiana Jones movies are realistic); something like spears or spikes:

    [Source]  [Source]  [Source]

    pointing toward the inside.

It’s not important that any of these actually be appropriate for or commensurate to the danger that’s within; it’s only important to convey the message that the builders of the prison thought that the demon was dangerous.

There’s a concept in physical security of “security in depth”: protecting physical assets with locked doors, fences, human guards, dogs, motion detectors, etc.  Computers have similar layers of defense, such as firewalls, compartments, containers and domains.  This answer represents an “in depth” approach to the psychological aspect of this problem.  After 99+ millennia, the best schemes for documenting the evil may break down.  Even if the warnings are understood, some people will defy them, perhaps believing them to be a deception, intended to keep people away from something valuable (like the warning signs that muggles see when they approach Hogwarts).  The techniques described in this answer should be easily understood 100K years from now, and might convince people who (willfully or otherwise) are not deterred by the other warnings.

  • $\begingroup$ Neat ideas! The only problem with having a sunken area is that it will fill up with soil or sand over the centuries. $\endgroup$ – Harabeck Mar 2 '18 at 22:36
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    $\begingroup$ Thanks.  You make a good point.  Would Aztec or Ancient Egyptian level technology allow building a roof over a large area?  (I’m thinking the size of a current-day major league sports stadium, but, depending on the size of the actual prison at the center, a few hundred square feet might be enough.)  After all, the whole point of locked / barricaded doors is lost if there’s no roof. $\endgroup$ – Peregrine Rook Mar 3 '18 at 4:40

Over a hundred thousand years, civilizations can raise and fall many times.

In times of low to middle civilization, the "protected vault must mean treasure" reflex will overcome any message you may leave.

Only in highly civilized times will people even look at the message before fetching their pickaxes. And the ancients knew this.

Make it inaccessible

To protect the vault in bad times, make it inaccessible without high technology. Since you have limited the technology of the vault builders, I see only one way they can do that:

Dump it in the sea.

They would need a prison that is small and light enough to fit on a ship. They did not need to be able to actually toss it overboard as they can sink the whole ship. One can only hope they brought another ship to bring the crew back.

Ships at the time weren't very sea-worthy so they could not go very far from the coast. This limits the depth you can dump the thing. There is also the risk of the land rising and exposing the wreck and the vault. If, for example, they dumped it in the Mediterranean Sea and the Gibraltar Strait closed, lots of sea bottom would become dry land.

Let us assume that the ancients foretold a time would come when people would be able to get at the thing, so they still left a message for the future.

The only symbol for death and danger that is truly timeless is skulls and skeletons. Engrave the thing with lots of skeletons. Many enough that people understand it doesn't mean "contains skeletons" but "causes skeletons, lots of skeletons".

Write it up

One of the technologies Egypt had was writing. Write up the story of how the Big Bad was captured and imprisoned. Describe the prison in enough detail that people will recognize it when they see it. Do not write down where to find it, since there is always that one idiot who will go looking. "Dumped at sea" is enough for that part.

Make as many copies as you can, translate into as many languages as you can, spread the word! Make the copies as durable as possible. That means stone engravings in protected locations.

Pray that people will keep spreading the story without too much distortion in the millennia to come.

Speaking of praying, this story will probably spawn a religion. This is both good and bad, as religions are good at keeping stories alive, but very bad at understanding and interpreting them. Translations done by religious people will tend to distort the story towards what is the accepted theological truth at the time.

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    $\begingroup$ Your answer is interesting, but... archaeology. The curses on King Tut's tomb were ignored for the bogus superstition they are. Eventually, people will stop believing in gods, and open the damned thing up, just to see what was in there. $\endgroup$ – RonJohn Mar 2 '18 at 2:16
  • $\begingroup$ @RonJohn: In the world this story is set in, there is such a thing as powerful Evil that needs locking up. In that world, not all superstitions are bogus. Perhaps an advanced society will still know that fact, and take warnings of Evil seriously. Unless this Evil was / is the only instance of magic / supernatural in the whole world. $\endgroup$ – Peter Cordes Mar 5 '18 at 8:52
  • $\begingroup$ @PeterCordes advanced, technological societies quickly forget the traditions of their ancestors. And even if this society doesn't advance, it's a big world, and 100,000 years is a long time. There's no reason why the civilization that built the tomb-prison didn't die out in 3-4,000 years. $\endgroup$ – RonJohn Mar 5 '18 at 9:02
  • $\begingroup$ @RonJohn: Right, but presumably there are other Evils that come along occasionally, and if they're real then advanced society will have to contend with them too. It sounds like you're assuming the future on this world will be like Buffy the Vampire Slayer or various other modern fantasy settings, where only a select few know that the supernatural is real. My point is that this isn't necessarily the case. Also, the Ancients will definitely not have any reason to assume that people in the future will forget (what they consider) obvious facts (that Evil exists), so they might choose poorly. $\endgroup$ – Peter Cordes Mar 5 '18 at 9:15
  • $\begingroup$ @PeterCordes "but presumably there are other Evils that come along" That's not in The Question. "you're assuming the future on this world will be ... where only a select few know that the supernatural is real." Sure. Look at our world: the supernatural might exist, but where's the evidence? "so they might choose poorly. We can agree on that. You've got to remember The Question: how can stone and chalolithic people warn people for 100,000 years? How much has the world changed in the 3000 years since Egypt was the mightiest empire? The Aztecs? 600 years ago. $\endgroup$ – RonJohn Mar 5 '18 at 9:24

Considering if you show humans a big red button and tell them not to ever press it, under any circumstances, you will find the button being pressed within 2 minutes:
Do Not Warn Them!
Sounds nonsensical, but is making the place where the Big Bad is locked really really really uninteresting, out of the way and very boring an option?
In addition, you could leave interesting but less dangerous things around, and warn about THOSE! Hopefully, this will gain you the required timespan.


Salt the earth.

Judges 9:45.
And Abimelech fought against the city all that day; and he took the city, and slew the people that was therein, and beat down the city, and sowed it with salt.

A warning will bring adventurers. Dead kings post curses all the time to keep away tomb robbers. Any sign of ancient works will get people interested. Maybe inside there are relics? Pieces of metal? Someone was here long ago, and cared enough to build something and maybe that building contains something I can sell, because I am hungry.

In ancient days, conquerors salted the earth to symbolically drive a stake through the heart of the conquered place. For your needs, evidence that there is poison in the ground will keep people clear. The ground should be poisoned so nothing will grow, ever. There should be no symbols, buildings, signs or anything else. The lack of life will be the sign that this is a bad place for life.

Later peoples may or may not know that the toxic place is the doing of people who came before. They might think it is something natural - good. If there is no evidence of ancient artifacts there is no reason to look for treasure. If nothing grows there is no reason to look for food. If it seems like it is poisonous there is good reason to stay clear.

enter image description here https://www.theguardian.com/environment/gallery/2015/apr/15/rare-earthenware-a-journey-to-the-toxic-source-of-luxury-goods

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    $\begingroup$ But will salt last 100,000 years? Europe had been both an ice desert and a jungle in prehistoric ages. Is there a bulletproof way to sterilize a ground for such a long period of time? $\endgroup$ – kikirex Feb 28 '18 at 22:44
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    $\begingroup$ At some point people will start to extract that salt. $\endgroup$ – Clearer Mar 1 '18 at 8:31
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    $\begingroup$ At some point people will start to extract metal too. $\endgroup$ – kikirex Mar 1 '18 at 21:51
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    $\begingroup$ @kikirex: who would want crappy cadmium? $\endgroup$ – Willk Mar 2 '18 at 1:45
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    $\begingroup$ @Willk "Salt will not but heavy metals could. One can find persistent metal contamination in the soil associated with ancient mines." by the very fact that we've tramped all over these contaminated places, your very comment proves itself useless. $\endgroup$ – RonJohn Mar 2 '18 at 1:57

If you want some ideas, look up how modern governments are trying to secure nuclear waste dumps for similar time spans.
Written warnings and pictographs will be no use at all, because no language will survive that long and there is no guarantee that people will understand a warning symbol.
The best Idea is to try and make the area as inaccessible as possible whilst also trying not to make it look like there is something valuable hidden there

this article describes the current thinking

Ultimately, the decision for the WIPP markers was motivated by cost-effectiveness. Current plans call for the area over the waste storage panels to be outlined by “earthen berms,” which is another way of saying “large piles of dirt.” These berms will be jagged in shape and will radiate out from a central, generally square area. The jagged nature of the berms is meant to convey a sense of foreboding, and the exact size, shape, and configuration of the berms will be such that they will not quickly be eroded or covered. The four corner berms will be higher than the others to provide vantage points to see the area as a whole. Inside the corner berms will also be buried concrete rooms containing highly detailed information, such as maps, the periodic table, and astronomical charts indicating the date that the facility was sealed. This data will be engraved upon stone slabs which are too large to be removed from the rooms’ entrances.


who's to say ancients haven't done this, we have Egyptian hieroglyphs and we have stories about their mythologies, a good myth can have morals or warnings of things to avoid

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    $\begingroup$ Especially when you write them down in three different languages on the same stone. $\endgroup$ – Mazura Feb 28 '18 at 0:48
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    $\begingroup$ Or in 66 different books (Bible?) $\endgroup$ – The Mattbat999 Feb 28 '18 at 1:51

First @Alexp has some good ideas listed but I am going to take a different perspective.

Pretend you bury the ancient evil in 5000bc, and evolution occurs at the same rate and we end up where we are today in terms of technology.

In the last decade or so sapphire disc have been developed that last 100,000 years and all you need to read them is a microscope.

Once you reach 2017 you can make copies of the sapphire disc for about $200-$500. This means making 10,000 copies and storing them all over the world is no problem at all. You can engrave something like 10,000 pages of text, enough to record it in every known language and in countless derivatives of said languages.

This means our real problem is only from -5000 to about 2017, and visiting the worst case scenario the year 3000. So a max of 8000 years instead this 100,000 year business.

By the year 3000, or before we should be able to bundle up said evil, and launch it into the sun, or if it can absorb energy to live then mars, pluto, or etc. Then if it escapes those planets are already destroyed and life less so who cares.

Today we have radar,lidar, and even muon detectors to map out the structure, and the nature of said ancient evil so we will be able to know a lot about this ancient evil and how to contain it. Also any information recorded today is unlikely to ever be lost with the exception of a extinction level event.

So once we launch the ancient evil into outer space we can stop worrying about it because we won't be able to reach it at all if we have an extinction level event.

So starting in 5000bc you will have to have an active civilization around this tomb, for lack of better word, to maintain it as long as possible. As Alexp mentioned large curved stone tablets with writing and room to re-write it every 10-50 years or as necessary to the language changes.

The writings will have to be interior and exterior, but I expect most of the exterior writing to erode over time. The structure will have to be many times thicker than necessary to allow for erosion. If the air gets polluted and/or has too much moisture erosion will happen many orders of magnitude faster than you initially planned for.

You will have to have a civilization build a city around/near it to guard it on all sides. Like a cult or religion that passes their beliefs on from one generation to the next. They will have to convey the warning to all those that approach. They will have to transcribe everything into all new languages and etch that into new stone. Also make books when they are eventually invented.

Your best bets are to bury it deep within the sand,water, ice shelf, lava, or perhaps arrange avalanches from a nearby mountain to truly bury it.

1-2mi deep, water, even a lot less than would be completely inaccessible.

Ice even 200ft deep, even today we don't dig that deep in ice, except maybe a few ice cores.

So hopefully your cult, and burying it will last you till 2017 at which time you can probably launch the "evil" into outer space.

  • $\begingroup$ I think it is not a good idea to launch the "evil" into outer space, for the same reasons we do not do that with nuclear waste. $\endgroup$ – Volker Siegel Mar 1 '18 at 8:32
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    $\begingroup$ The OP said it was evil, which is actively bad, and nuclear waste which is passively bad. @VolkerSiegel if we send it to pluto or the sun it will surely die there eventually. It has no where to go, and it will definitely be contained for 100,000 years requested. The "evil" won't be able to achieve orbital velocity so it stuck. $\endgroup$ – cybernard Mar 1 '18 at 12:44
  • $\begingroup$ I like the basic idea behind this which is basically a hopeful society believing that at some point in the future their ancestors will discover a way to deal with the evil. However, from the perspective of a few thousand years ago, there is no way that you would assume you can launch something into the sun. $\endgroup$ – Tom Mar 4 '18 at 6:47
  • $\begingroup$ @Tom "from the perspective of a few thousand years ago". The OP said the ancient evil is already trapped. We have to keep it trapped until 2017 ( or etc) when we can actually launch it into the sun. So instead of the impossible 100,000 years we only have to manage 7000-8000 years. $\endgroup$ – cybernard Mar 4 '18 at 17:16
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    $\begingroup$ @cybernard look back yes. But looking forward, the people living a few thousand years ago had no way to know that in 2017 we would have space rockets. That was the point $\endgroup$ – Tom Mar 4 '18 at 23:51

Damage or hurt slightly anyone approaching the site

Besides the warning signs/monoliths (which may be dug out by archaeologists several thousands of years later, even if they depict warnings), there could be a non-deadly trap system that would hurt the intruder physically and/or psychologically. A couple of examples:

  • archaeologist approaches one of the entrances of the complex and a trap door/step would simply make him fall on the ground where solid and heavy rocks would depict deeply carved dead or suffering animals/beings;
  • drone approaches the place and a certain semi-closed area would have a magnetic/electric field (or radioactive material?) that would disrupt electronics and once it passed through, similar rocks from above would be seen.

Supposedly Egyptians had some knowledge about electronics, therefore with a big enough battery zapping them could also be a way to scare off primitive animals as well.

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    $\begingroup$ How do you imagine these to survive 100,000 years? $\endgroup$ – Mołot Feb 28 '18 at 13:11
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    $\begingroup$ Somehow I interpret the "hurt the intruder psychologically" as: "first dude on the sacred hill is a douche!". $\endgroup$ – kikirex Feb 28 '18 at 22:53
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    $\begingroup$ Note that given limited technology, it may take the actual 'evil' itself to do the hurting. Lock the main evil in a way that it can hurt people coming close, or surround it by so many lesser evils, gradually increasing in strenght as you get closer to the main. That way people will know what they are getting into by the time they reach a spot where they can unlock the main evil. $\endgroup$ – Dennis Jaheruddin Mar 2 '18 at 10:24
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    $\begingroup$ Just wanna point out that your link about the Egyptians is bollocks. It's an example of forcing modern ideas onto an ancient image. You can find our understanding of the actual symbols here: ahotcupofjoe.net/2016/11/… $\endgroup$ – Harabeck Mar 2 '18 at 22:41
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    $\begingroup$ @Harabeck one could say the same to the link you provided: it ends with questions as assumptions, it's based solely on 3 old references, no mention of the Pharos Lighthouse, nor the Indian battery instructions and disregards that: "the stem of a lotus flower does not grow horizontally along the ground, going off to a source and then rise suddenly and vertically at 180° angle to connect to a mysterious bulbous form (...) and it doesn't require devices resembling high voltage insulators to support their weight". To have as "proof" the fact that archaeologists didn't find glass is laughable... $\endgroup$ – Armfoot Mar 3 '18 at 0:39

How about a set of huge tetrahedral monoliths in the pattern of the constellation from which the danger came (maybe with square bases for better stability though). Oh wait..


that can be easily comprehended by anything and anyone, considering how much >language changes in only a few thousand years.

First of all, it would be impossible to create a universal message to include "anything" because you have to start with some commonality. Assuming the ancient and future race are both human and only the normal 5 senses available (no esp) then the message will be visual. The prison should have an obvious entrance marked with a symbol on the door. In a three panel image, Panel 1: Show the closed door with symbol, several people and animals. Panel 2: Show Person open the door. Panel 3: Show open door and skeletons of humans and animals to indicate death.

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    $\begingroup$ I believe variations on this have been tried by just about every Pharaoh. Any guesses as to how many Egyptian tombs haven't been looted? $\endgroup$ – Mark Mar 2 '18 at 1:18
  • $\begingroup$ I was thinking the same thing.  In fact, signs like this exist in the real world, now; see this [source] and this [source]. $\endgroup$ – Peregrine Rook Mar 2 '18 at 6:57
  • $\begingroup$ This also presumes that future people will be able to understand the idea of a comic strip. $\endgroup$ – Albert Newton Sep 14 '19 at 10:35

I have not seen it yet but its mostly an augment to the "leave no trace" suggestions that appear.

To keep something from being opened would be to remove it from existence. Not in the literal way of course but in everything. It must be wiped from texts, myths and legends so no trace of it remains. Everything leading up to the event must be expunged so that there is no "sudden dead end" in texts a la "there is a page that is missing" trope. Even if the place is opened and the object found, don't make it look different than everything else. that makes people go "ooh, it says not to open it but it's the only container with writing so lets open it." If some destroyed city plays prominently into the how it happened, take it apart and use the stones for something else like building a wall around a city or some such or if it can't be safely re-used for permanently structures, move the city. The easiest example that comes to mind is as mentioned previously regarding the tomb of Genghis Khan where the workers were killed by the guards who reported their success to another group of guards who killed the first set of guards. This effectively hid the location of the tomb to this day. Of course, we know about it so part of this explanation is already compromised which is the "this page is missing" part you are trying to avoid.

It could be taken a step further by creating some sort of group that scouts that spot but also many others to help throw people off. They don't have to look like soldiers or warriors outwardly but they must be ready to ward people off who stray or stay too close. An example that comes to mind would be the Medjay from The Mummy (1999) which did a terrible job since they would loiter near the hidden city all the time leaving a marker so to speak but the premise is sound.

I suppose though that this does not serve the purpose of your request as to warn people so I apologize if this is lacking any assistance.


The obvious thing is Locks an/or puzzles,

Some things like having various artifacts that must be used together to unlock it, so while it's easy to unlock with all the "keys" without those it would be very hard.

The same with a puzzle in order to understand the puzzle you may need some context about the ancients, once you have that context you would know that opening it would be unwise. Things like language, so in order to understand the puzzle you would need to understand the language and once you understand it you would have the knowledge to be warned about opening it as well.

Just some thoughts.

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    $\begingroup$ With modern tech you can brute force just about anything that an ancient civilization could create. $\endgroup$ – mislavcimpersak Feb 28 '18 at 8:59
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    $\begingroup$ A puzzle or a lock can be interpreted as a challenge or as a signal that something worthy to be guarded is held inside. Both would actually motivate people to open it instead of turning them away. $\endgroup$ – zovits Feb 28 '18 at 14:23
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    $\begingroup$ To the average person, puzzles and locks scream "treasure hidden inside", at which point they'll bypass the lock with a pickaxe or a pile of dynamite. If you're trying to keep people out, that's just about the worst thing you can do. $\endgroup$ – Mark Mar 2 '18 at 1:17
  • $\begingroup$ Your not telling me anything I dont know, nor anything anyone else has not said. As a point of plot, it's probably one of the better options, sure we could dig a mineshaft thousands of feet deep bury it and erase all traces of it, but that doesn't work well in a story. There is a presumption that it will be found. There is also a presumption of magic or the supernatural which could easily prevent brute force methods. $\endgroup$ – ArtisticPhoenix Mar 2 '18 at 1:55

drawings would last a long time, especially in a cave. drawings are universal so that is the best option. they would have to make a lot of drawings though to convince the future of the danger.

  • $\begingroup$ Drawings are hardly universal. $\endgroup$ – Mark Mar 2 '18 at 1:22

There's probably a formula to back this up, but as a rule, the amount of insistence made not to do a thing (Don't go there, Don't open that, Don't touch that, What did I just say?) Is in inverse ratio to the attention paid to said warnings by later generations and civilizations.

One of the most fraught with portent sentences ever uttered is "Oh, it can't be THAT bad..."

  • $\begingroup$ This is generally true, but would you be able to add how the ancient race could warn the future one despite this? $\endgroup$ – Mithrandir24601 Feb 28 '18 at 21:00

There is this theory in acoustics, that if malleable material like clay is exposed to sound, it creates minute vibration marks on the object which can be read with specialized instruments. Therefore, a Morse code message embedded in a clay disk might just work.

  • $\begingroup$ Why would this be any more durable than normal writing on a clay disk? "Minute vibration marks" would wear away much faster than normal engravings, and Morse code just adds an extra layer of encoding/decoding on top of a written language. Recording actual sound might have advantages, if the Evil sounds obviously evil, but like I said "minute vibration marks" probably won't survive 100k years very well. Using it to record the sound of Morse code completely defeats the purpose. $\endgroup$ – Peter Cordes Mar 5 '18 at 9:10
  • $\begingroup$ That's why you can record it over and over in a looping message. At least one loop can survive. And Morse Code isn't neccesary. Just an idea. $\endgroup$ – Budhaditya Ghosh Mar 5 '18 at 11:03

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