Let's say that there are 2 countries with very different inhabitants. Country A has no idea that country B exists. Country B may or may not know about Country A. Country A is surrounded by large mountains and has no sea access. Country B is quite far away, on the other side of the mountains. The mountains are only inhabited by wild and dangerous creatures; there is no organized border between the two countries.

The two countries are both the nearly eternal medieval society without gunpowder and with few scientists. There are quite a few other countries on the continent, but none of them has contact with both A and B. Most are in contact with B only.

Around 1000 years ago the two countries (A and B) used to trade and fight together (as allies against a common enemy which they vanquished). Now, however, Country A has forgotten this history and doesn't know what is beyond the mountains.

What properties of my world could lead to Country A losing touch with the rest of the world like that? There is no magic, so no magical spell to make them forget.

How could that situation be possible? Country A not knowing what is on the other side of the mountains?

The main reason I have is that since the trip through the mountains is very difficult, they simply stopped doing it. Being an early medieval civilisation, they did not use much written archives. And in a thousand years they simply forgot the oral memories and it became legends.

I find my explanation very weak and unbelievable. Do you have another explanation for why this loss of common knowledge would happen?

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    $\begingroup$ Thank you for the answers. kepltx No tampon states. Just some wild and dangerous creatures. @ironduke97 yes, allies. secespitus, yes country B is at a similar stage of development. The nearly eternal medival society without gunpowder and with few scientists $\endgroup$
    – Dreamk33
    Commented Jul 17, 2018 at 8:13
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    $\begingroup$ Are there other countries on this continent or just A and B? I'm asking because it would be less plausible to forget this other country exists if there is a country C (maybe over a sea) which trades with both. Also, medieval cultures on Earth did have written records, even if only a small percentage of the population could actually access and read them. It is also quite a different thing that this small percentage was in the habit of arbitrarily changing these records in their copies to suit their politics. $\endgroup$ Commented Jul 17, 2018 at 10:42
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    $\begingroup$ Reminder to close-voters: The problem cannot be fixed if the OP is not made aware of it. $\endgroup$
    – Frostfyre
    Commented Jul 17, 2018 at 12:32
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    $\begingroup$ @Dreamk33 putting a question on hold is meant to be temporary; ideally the question is edited to address whatever the concerns were and then reopened. Please see the link in the hold notice. Members of the community will be happy to work with you if you'd like. I edited the information from your comments into the question. $\endgroup$ Commented Jul 18, 2018 at 2:53
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    $\begingroup$ The reasons why two nations might lose contact with one another looks on-topic to me. An implausible reason could break the immersivity of the setting. Voting to reopen. $\endgroup$
    – Monty Wild
    Commented Jul 18, 2018 at 4:20

9 Answers 9


There was a mountainslide...

...which is like a massive landslide but more of it. It left the mountain range so steep, rugged and imposing that no one dared get close to them.

This could have happened during the War (1k years ago) or a later date. I'd say not to choose a date more recent than 100-200 years, so the current generations don't remember (or believe) about the exterior cultures.

First, it was the fear that stopped them. Fear of the thing that caused The Mountainslide. Fear of the gods or whatever mystical or natural force they think caused it.

Then, new generations tried to cross the mountain range. They stopped fearing that force and started to consider it a legend. But there was no way to cross them. Whenever you think you were close to the other side, or you had found a promising path, you'd find an abyss, a crevasse or an almost vertical wall.

Then, when all hope was starting to vanish, they found the caves. A whole universe of caves and underground galleries were created by The Mountainslide. Wonders and valuable stones no one had seen before lied down there, which attracted the explorers... and the merchants (who didn't go themselves but paid other people to go). Many people disappeared in them but some returned, and a map has been created over the years.

This probably was a nation-wide effort, both to make the map and to overcome some obstacles (bridges, new speleology or clothing technologies, etc...). There could also have been some private parties doing their own maps and selling maps technologies between them. It has taken many many years, decades or even centuries. Even with current technology, there are plenty of cave systems not fully explored.

Now, after (X) years of exploring, they're about to find an exit...

...which will reunite them with an exterior world they no longer remember.


There's actually a pretty good real-world example of this: Tokugawa (Edo) Japan.

Starting in 1633, the government of Japan instituted a policy of seclusion. Fearing foreign influence and especially Christianity, they banned all foreigners from entering*, and all Japanese from leaving Japan for over 200 years. Crews of foreign shipwrecks were executed. Japanese fishermen who were blown off course were not permitted to re-enter. Merchants were not allowed to trade abroad.

Although the Tokugawa government leadership knew of the outside world through ambassadors from the Dutch, Chinese and Koreans (who were permitted to send envoys to the Shogun and trade at a few ports), by the end of the policy of seclusion the average Japanese person had never met a foreigner, had never traveled abroad, and likely had only vague ideas about what was outside of Japan. In some cases fanciful legends developed about foreign countries. (Some Japanese thought that Europeans were meat-eating devils who sweat butter for example.)

So, one way that your situation might be possible is some kind of strict government or religious authority which prevents people from Country A from travelling beyond the mountains. Over time few people even remembered what was over there. Legends abound about the barbarians over the mountains.

*(with some exceptions. certain foreigners were allowed to enter at one of four ports, where they were segregated from the local population. Once a year they were permitted to send an envoy to see the Shogun.)

  • $\begingroup$ Welcome to WorldBuilding mklingen! Interesting real life perspective on the question. If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$
    – Secespitus
    Commented Jul 17, 2018 at 13:36
  • $\begingroup$ While ordinary japanese didn't know anything about the external world, they did know there was an external world. They may have not visited China, but they knew it existed and the wars they fought against them - the "kami kaze" that saved Japan from the invasion. The very executions of foreigners is a proof that foreigners existed. And besides, the only reason the shogunate could get with this is that Japan is an island. Had it been in the continent they would have failed to prevent infiltrations. $\endgroup$
    – Rekesoft
    Commented Jul 17, 2018 at 14:45
  • $\begingroup$ Yeah it's not a perfect analogy because of course they knew that the outside world existed (even if they might be very ignorant about it) but you could imagine similar scenarios that the OP describes in a fantasy setting. $\endgroup$
    – mklingen
    Commented Jul 17, 2018 at 14:49
  • $\begingroup$ While the Tokugawa Shogunate was isolationist, it's not to the extent that you imply here. Throughout this period, they still traded with China, Korea, and the Netherlands. Basically they restricted who could trade with them and where they could interact with each other, but didn't cut themselves off completely from the rest of the world. Throughout this time, they occasionally had to enforce this policy with force as well, so there are more interactions with foreigners. $\endgroup$
    – kuhl
    Commented Jul 17, 2018 at 16:33
  • $\begingroup$ It's worth noting that trade with the Chinese, Koreans and Dutch could only happen at 4 ports in Japan, where they were strictly segregated from the local population. $\endgroup$
    – mklingen
    Commented Jul 17, 2018 at 16:40

The people in country A could have a religion saying that demons live beyond the mountains, and if someone crosses they will not only kill the travelers but attack country A. So they set guards to prevent anybody from crossing. This wouldn't be perfect, but with the religion popular enough

  1. People who don't believe in it can't say so, or they risk death.

  2. Anybody caught trying to cross the mountains is executed.

  3. Those who try despite that generally get lost or die on the way.

  4. Those who do get to country B get treated to their version of the religion which considers them to be invading demons (optional).

  5. Anybody who manages to cross, see country B, escape and get back, and then tries to tell about it without being very careful gets executed again. Demons obviously messed with their mind, after all.

The religion could be based on the misremembered war as well.

  • $\begingroup$ Hello, AlexeyRomanov, and welcome to Worldbuilding.SE! Please take our tour and visit the help center to learn more about the way the site works. Have a nice day! $\endgroup$
    – Gryphon
    Commented Jul 17, 2018 at 12:00
  • $\begingroup$ @sgroves, a welcoming comment to point a new user towards resources to help them understand the site better is pretty standard practice on Worldbuilding. I'm certainly not the only one who does it. $\endgroup$
    – Gryphon
    Commented Jul 17, 2018 at 16:17

A mountain range, no matter how big, wild and dangerous it is, is no obstacle for an adventuring race as curious as us humans. Someone would try to get through just because reasons, or as Sir Edmund Hillary put it: "Because it's there". Many (most, if you want it so) would die, but some of them would get through - and back - and they would ensure that at the very least the knowledge of something existing on the other side would not be lost.

The only thing preventing that would be a 100% fatalities in crossing, but that's hardly believable. If some deadly creatures did that, there would be a great interest in both countries A and B to destroy these creatures, since they inevitably will expand into both countries' territories - whether they are animals, plants or supernatural creatures; and if it's some non-living threat such as a chasm or a deadly river, or temperatures, or whatever you want it, somebody would find a way to counter it.

If your world had magic, that would do it, but since it doesn't I can only find two possible impassable barriers (impassable to a medieval civilization, that is): chemicals and radiation.

You can have your mountains being mainly active volcanoes. Rivers of lava make the crossing impossible except at certain points, but these points are deadly traps: the CO2 condenses there, especially at night, when it's colder, and suffocates everyone who is in there. Since you need several days to cross the mountains, it's impossible to get through without dying. Doubly so to get back to report if you did it.

A subtler variation of the theme is a lot of radioactive isotopes on the surface. You can get almost there without seeing or noticing anything strange, but when you are about to get through the last mountains you start feeling sick and feeble, and you die (horribly) just watching the valleys of the other side of the mountain range a few miles away.

  • $\begingroup$ That is a very nice answer, upvoted, thank you very much. However it does not seem to satisfy my need, because I do need a group of people to be able to cross this boundary in the present story. Such a deadly solution would make it impossible to travel later on. I was hoping for something like a reason for country B to make sure that nobody enter/leave their territory. $\endgroup$
    – Dreamk33
    Commented Jul 17, 2018 at 10:13
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    $\begingroup$ @Dreamk33 To do that, Country B must know the existence of Country A. $\endgroup$
    – Rekesoft
    Commented Jul 17, 2018 at 10:17
  • $\begingroup$ Yes in the original question I wrote "country B may or may not know about country A" which means that both scenarios are possible, whatever helps to have a nice solution. It is only country A that has to be in the dark ( or at least 99.99% of the population.) $\endgroup$
    – Dreamk33
    Commented Jul 17, 2018 at 10:26
  • $\begingroup$ ` Many (most, if you want it so) would die, but some of them would get through - and back - and they would ensure that at the very least the knowledge of something existing on the other side would not be lost.` Well, that could happen inside the story. We just need an obstacle that will stop people for enough time to forget about the outside. 100 years, maybe? 200? On medieval times there were a few places on Earth still unexplored. $\endgroup$
    – xDaizu
    Commented Jul 17, 2018 at 11:46
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    $\begingroup$ @Rekesoft just a note about your impassable barriers, while I agree this type of thing is the only real way to prevent explorers from passing through the OP does mention that the two countries fought together before so radiation might have to be ruled out, if the volcanoes only became active after their fighting together that could certainly work. Perhaps there was some sort of cataclysm that woke the volcanoes? $\endgroup$
    – BKlassen
    Commented Jul 17, 2018 at 19:22

I think your initial idea is good, perhaps there's some sort of dangerous animal prowling, preying on people who entered and they eventually made it taboo to enter the forest. Perhaps they created a scary tale to scare children off from entering it (like the boogeyman). But in addition to that, you could throw in this idea, about 500 years ago:

There could have been a plague that swept through the country and the younger generation was immune/not as affected. While parents and adults were sick and feeble, unable to do work, the younger generation had to step in. It was during a harsh winter which made things worse. The younger generation used everything they could find, burning books and furniture to keep their houses warm so that way they could try to survive.

That took up their main focus, they weren't thinking about history, just survival. And once you stop thinking about things for awhile, you eventually forget. With the focus on saving people and survival, the conservation of knowledge fell to the wayside. The elderly who held the knowledge died, as did many other adults, and the majority of written knowledge was lost. The years spent after were focused on rebuilding and population growth.

I feel that in medieval times, people would have worried about the short term - surviving now, than the long term - what are we going to do after?

The very very few books found thereafter could be thought to be fairy tales, like the boogeyman.


There was a flood...

Maybe it was caused by a big earthquake, a tsunami, a volcano erupting, or just a sudden (geologically speaking) temperature rise which melted a lot of ice, and country B was suddenly flooded with enough water that the cities and villages and agriculture that wasn't destroyed by the water was destroyed by lack of food and diseases that followed. Maybe country A only waited to see the actual flooding and decided country B no longer existed because [insert appropriate gods' name] destroyed it for their sins and everyone who tries going there is automatically damned. Superstitions do hold strong in medieval societies, especially if the road there is already fraught with dangers.


What if Country A just isn't that good? Or if Country B is full of ecstatic pleasures? Maybe some do successfully cross but the fact that some don't and the fact that all who leave never return make it so the information doesn't come back.

Country A may be a great place for the conservative mind; people who are avoiding dangers and preserving their society; while those adventurous enough to dare the mountains not only self-select their more liberal mind out of the country but when they arrive at Country B and find an amazing plethora of new things to try, why would they ever leave?

Depending on how political and metaphorical you want to get, you could have each show you the pros and cons of highly conservative vs highly liberal places; much like the Eldar and Dark Eldar do in 40k[1].

[1]NOTE: 40k is universally GrimDark, so a frame of reference adjustment is required before considering that perspective.

Regardless of whether you want that metaphor, the two styles of thinking lend themselves to the societies they're in. The more conservative thinkers will be happy in their mountain-protected area; having everything they need and being mindful of how to preserve it. The more liberal minded among them will want to adventure out and either die trying or be successful. Either way, it's likely they don't come back (especially if the mountains are that harrowing) simply because there's more to explore; or more pleasures to enjoy, or more things to experience on the other side.

The fact they don't come back looks like they're dead, so it reinforces the culture that crossing the mountains is a death sentence. You build that legend up long enough, anyone who does come back may look like a Heretic, a liar, etc.

This, in that proposed political take, would allow you to see the dark side of conservatism (the authoritarian enforcement of customs and values) where these "liars" are dealt with. On the flip side, Country B may have issues with diseases, debauchery, and lack of social cohesion - possibly having infighting due to that.

Regardless if you like that idea, I think the seeds are there for you to see how a colony may self-select to keep itself in a safe place and reject those who would claim there is more to the world. What's more? this is quite easily done with a religion; where their paradise between the mountains is the world - a god given region surrounded by the hells. The lavish beasts in the mountains are god's punishment for those leaving, and the frozen wastes are warning to avoid the betrayal of this wonderful place.

As goofy as it sounds, my interpretation of your story is basically the Country version of The Fox and The Hound; maybe the two civilizations do eventually reunite and fix each other's ills or delusions.


Another option: climate/tectonic change.

A thousand years ago the mountains were rugged, but passable, and trade happened across them.

Then over a hundred years or so, a sudden cooldown of the climate and/or volcanoes and/or earthquakes made the mountains no longer passable. Volcanoes and earthquakes have the advantage of being a sudden, dramatic change; climate cooling has the advantage of being both durable and reversible. Any of those can also have the bonus that they'll have disrupted the society of Country A enough to justify forgetting the past. Massive decreases in population, political unrest, having to burn books for fuel... Basically, people would be too focused on survival to keep alive the memory of Country B, the existence of which has become entirely irrelevant to their lives. This can obviously be combined with the more deliberate isolationist efforts suggested in other answers.

Then after a thousand years the climate could start warming again, to the point that going into the mountains would be less insane, and increased population might mean more crazy people to try in the first place, and it would also be a more attractive prospect to people who are no longer as focused on pure survival. Or another tectonic event could make it passable again in a more sudden and dramatic fashion.


There must be much more than just something between them. Because, as you probably know, you can go around them.

General direction you want to look at is Greece. Hard presence around any water but almost no in deep land. And Greeks were so content with their wine, olives and feta that no one bothered to check Olimp for god presence till early XX century.

So, for example, looking at map. Greeks could known and consider neighbours nations located in Arabian peninsula. Because there was connection between Mediterranean and Red Sea. Then, some natural cause closed the watercourse. And because people where very superstitious and not keen to walking long distances they forfeit looking for land connection. Kind of like Gibraltar rocks in mythology (Maybe this story is about such event?)

  • $\begingroup$ Thank you for the answer, upvoted. No there is not really a way to go around the mountains. They are pretty much a circle around the whole country. This is for a fictional story in a fictional world, that why I have so much freedom. Country B does have large amount of water. But country A is landlocked. I see your point, and your idea is nice, I'll consider it thank you. $\endgroup$
    – Dreamk33
    Commented Jul 17, 2018 at 10:46
  • $\begingroup$ You can also look into old myths about "magic" gates that make travel forbidden. and because they are set in our world where magic is not present you have put natural causes explained by magic by inhabitants of yours. $\endgroup$ Commented Jul 17, 2018 at 11:06
  • $\begingroup$ Mount Olympus was a well-known touristic destination in the antiquity. I have no idea why anybody would believe that "no one bothered to check". The mountain is not at all hard to climb, there is a splendid view from the summit and there was actually a temple on top. The ancients were perfectly aware that myths were mythical. $\endgroup$
    – AlexP
    Commented Jul 17, 2018 at 11:48
  • $\begingroup$ Yet the first ascent was done in 1913. And no, there was no temple a top of it. It had REAL temple in it's foots. On the top there was mythological one. $\endgroup$ Commented Jul 17, 2018 at 12:07
  • $\begingroup$ That people didn't "bother to check" is a gross mischaracterisation. The actual peak is just quite difficult to reach and there's nothing of real value there. The ancient greeks were quite aware there wasn't a physical house with physical gods inside at the peak (that much would've been visible without climbing the thing). Presence around water is true for pretty much any higher culture - sustaining a large city with wells would be pretty ambitious in ancient times. And the greeks were aware of and interacted with their immediate neighbours, like pretty much all cultures do. $\endgroup$
    – Cubic
    Commented Jul 17, 2018 at 14:26

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