A small late medieval county, consisting of a very small town, a small castle, and a couple of surrounding small villages suddenly and inexplicably gets transported into the past. It's not a spherical volume with soil, they are just transported there with their houses, clothes and tools intact.

The destination would be geographically the same place, as near as it could be defined taken erosion, continental shift etc, into account. They will not appear below the ground or in the air, but on the surface.

They probably have some food to last for a couple of weeks, so they have that much time to find out what is edible.

How far back in time could this bring them to ensure their long-term survival?

  • A. if they have no seeds to plant and no livestock with them. Those are all left behind. They'll have to find things to eat, plants to cultivate, animals to hunt or domesticate.

  • B. they have all the seeds and livestock they had, this can also mean enough food to last for a couple of months if rationed well, probably enough to last until the first harvest, if a greater part of their seeds/livestock are consumed. This probably pushes the possibilities further back in time, until the existence of a soil and an atmosphere with a tolerable percentage of oxygen will start limiting it. Or will there be other limiting factors?

The time of the year is picked to maximize their chances of survival.

  • $\begingroup$ Are paradoxes allowed in your time travel scheme? The further into the past, the greater the risk of interacting with something that affects your own future time line. If paradoxes are allowed, that isn't a problem. If physics somehow blocks paradoxes, it might kill you off to prevent your interactions -- i.e., if there's no future record of a civilization in location X, you'll have to be wiped out entirely at some point. $\endgroup$
    – SRM
    Sep 30, 2016 at 18:19
  • $\begingroup$ @SRM : assume ring-of-fire style time travel, with creating an alternate timeline which now progresses completely independent of the original. $\endgroup$
    – vsz
    Sep 30, 2016 at 18:32
  • $\begingroup$ Does anyone know if immunity to disease would come into play? Are you in worse or better shape the further you go back? Once you get past a mass extinction event I feel like that's going to be a problem. $\endgroup$ Sep 30, 2016 at 19:06
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    $\begingroup$ @Cradle2theGabe : Even diseases completely new to a population don't routinely drive them to extinction, they rarely kill off more than a small percentage. I would guess that dozens or maybe hundreds might die, but the rest will carry on. Not an uncommon event in the middle ages. $\endgroup$
    – vsz
    Sep 30, 2016 at 19:17
  • $\begingroup$ @vsz: Makes sense. I read some related questions that essentially negate the notion that it would be significant. $\endgroup$ Sep 30, 2016 at 22:52

7 Answers 7


Assuming they don't land on the polar ice caps, in the middle of a desert, or during winter and an ice age, they can survive up to 430 million years ago, the approximate time period of the evolution of woody trees. So long as humans have wood to make spears, they can out-hunt any other predator in existence. Of course, I wouldn't say their survival is assured, but it seems likely. There are always animals to hunt, and there will be many, many more in a pre-human world.

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    $\begingroup$ +1, But you might be able to go further. If there are rocks and some form of fibrous plantlife then they can make slings, which are arguably more lethal than spears if used correctly. Or jump even further back and become the only tidal pool scavengers capable of surviving on land for an utterly uncontested niche (though then you need to worry about atmospheric content and whether you can eat nothing but anemones) $\endgroup$
    – Joe Bloggs
    May 8, 2019 at 17:02

Just one possible answer--and definitely on the safer side--but I would say up until the last glacial period, around 12,000 years ago.

The local flora and fauna should be familiar enough to them where they could manage a type of hunter-gatherer existence. And there should not be too many threats in the form of predators, though you would be sharing the world with early humans. You also did not specify that the town must stay centralized so if they were to adopt a nomadic lifestyle this would be all the more effective.

I'm curious to see what other answers come up.

EDIT: My answer pertains to your "A" scenario. Though even with "B" you won't be yield enough (or any) food from crops in a "couple weeks" to feed your town. Depending on the population and how much/what kind of livestock is present it may be able to buy you the time you need to get your crops in order.

EDIT 2: The time of year matters. Winter would not be good.

  • $\begingroup$ You are right about the time of the year. It was in my mind but I forgot it. Updating the question. $\endgroup$
    – vsz
    Sep 30, 2016 at 18:34
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    $\begingroup$ 12,000 years is a very low number. The earliest known capability of humans sewing is 50,000 years ago wiki. Just because their technology hadnt advanced yet, doesn't mean the animals and plants necessary for domestication and agriculture didn't exist. 12,000 years is about the limit of known agriculture. Doesnt mean the plants didnt exist. That's just the first record we have of them being deliberately cultivated. $\endgroup$
    – Stephan
    Apr 8, 2019 at 19:30

The biggest natural danger would likely be microorganisms. Even if our time travelers could adapt to the land and weather, as well as mount a complete defense against the most ferocious of fauna, it will be the bacteria, viruses, fungi, and parasites who will win the day. Our immune systems will not know how to fight these long extinct organisms, and they will be teeming in the water, food, and soil. When we throw in direct exposure to humans of the time, who are likely to be immune carriers of ancient illnesses that we have never seen, the time will be short.

  • $\begingroup$ Welcome to the site blackcatweb, please take the tour and read up in our help centre about how we work: How to Answer Good first answer, curious that noone else had thought of this aspect. +1 $\endgroup$ Apr 8, 2019 at 17:27
  • $\begingroup$ There are also important microorganisms in our soil and food (and by extension us) that are needed for survival. I'm not sure what the implications of replacing a large portion of someones microbiome would be. (This is a big deal for potential Mars colonists, since there are presumably no native microorganisms.) $\endgroup$
    – StarHawk
    May 8, 2019 at 16:51
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    $\begingroup$ I’m not so sure about this. Go far enough back and there won’t be any diseases that can effectively attack humans. Our immune systems are stupidly powerful unless the disease has also been engaged in the evolutionary arms race. $\endgroup$
    – Joe Bloggs
    May 8, 2019 at 17:06
  • $\begingroup$ @JoeBloggs Agreed. Smallpox festered in filthy cities for centuries, specifically evolving to bypass our defences— and even then it didn't kill off all the natives in the Americas. Note too that there was no Americapox that affected the European colonists. It takes a lot of specialization to be able to infect a human body. Random bacteria won't cut it, and viruses, fungi, and parasites are even more specialized. You never hear about the fish flu jumping to humans. Therapsid and Archosaur germs from the Triassic won't have the tools to enter our cells. Doubly so for plant and rock bacteria. $\endgroup$
    – Will Chen
    Oct 25, 2021 at 20:28

1) The lack of bees, when you go far enough. Without bees crops that rely upon then won't reproduce. Pollenizer insects, IIRC, appeared first during the cretaceous, together with the flower plants. If you are lucky, these bee-like insects will be able to fertilize yout crops. 2) Heat. Humans would have a hard time living during the hottest time periods of earth's history and your villagers would die from heatstroke, like in the eocene, the cretaceous and the permian. 3) Oxygen. Some periods had much more oxygen then today, like the carboniferous. I don't know how their bodies will react to this. They may be fine or they may be dead. 4) Inbreeding. Villages have small populations to begin with and with the casualties they will suffer as they adapt to the environment, the population will drop. Inbreeding may kill them in a few generations.

The animals aren't a problem. Man is the deadliest hunter Earth has ever seen and your villagers will soon learn how to kill everything on their path. Even tyranossaurs, those giant insects of the carboniferous or the terrorbirds.

  • 1
    $\begingroup$ A problem with the “no bees = everything dies” theory is that its completely false. There are more natural pollinators than just bees. Without the bees, other natural pollinator populations would be able to grow, taking advantage of all that nectar that the bees have left behind. $\endgroup$ Apr 9, 2019 at 18:28
  • $\begingroup$ Good point for the bees. Inbreeding won't be such a problem, as a small town + a caste + a couple of villages and hamlets around will mean a population more than just a couple hundreds, and even so, there are many island communities which thrived for millennia with a population of a few hundreds. Less than a few hundreds will be a problem though. $\endgroup$
    – vsz
    Apr 9, 2019 at 18:29
  • $\begingroup$ Liam Morris, yes there are other pollinators. But there are no pollinators before the cretaceous period. So the crops aren't viable, say, in the jurassic or the carboniferous. Also, in the case of the grains that are the basis of medieval diet, heat matters. There are studies, in the context of global warmin, that indicate that high temperatures can reduce grain production by 50% or more. So even if you have bees, farming may not be viable in the eocene or other hot periods. $\endgroup$
    – Geronimo
    Apr 9, 2019 at 18:35

@Salmoncrusher, +1. I like the way you think.

Modern humans arrived in Australia at least 65,000 years ago, possibly somewhat before that. Evidence suggests that they were primarily hunter-gatherers though there is evidence of fish farming and cultivation.

I suggest that you could send them at least this far back without difficulty. They would have to cope with the endemic megafauna but hey, early humans drove these to extinction so a reasonably well equipped medieval county should not have any difficulty (look, big food). Also in this time frame familiar game would be abundant (rabbits, deer, pheasants, salmon etc) as not yet hunted to near extinction.

As for vegetable food sources, humans are omnivores, we can live, maybe not well but live, on a wide variety of plants, dandelions, ferns, seaweed, acorns mushrooms etc, etc. As you are placing them in their local area they would know, particularly the peasants, about these food sources.

Have them arrive in Spring, in time to catch the planting season, and plenty of new growth to live off. Is the local Lord smart enough to sequester all grain / seed stock for planting?

Yep, I'd avoid glacial maxima. Not going to survive under an icecap. There are plenty of interglacials to choose from however.

As for disease the vector typically works the other way with the more advanced culture infecting the less advanced, see what happened to indigenous populations in the Americas and Australia.

As an aside Julian May makes a pretty good case for earlier human survival in the Saga of Pliocene Exile. (The Many Coloured Land et al).


You can look into the fate of the Roanoke colony. Even the Plymouth colony only survived because they could eat corn reserves stored in granaries in the native villages where everyone was dead because of european born diseases. Chances are the time travellers will just starve to death. But, if you create a convincing enough streak of luck, maybe a few of them could survive the first season cycle and build the foundations of future growth.

  • 4
    $\begingroup$ Roanoke vanished mysteriously and as such is a bad example. Also the colonies were fool-hardy, had few supplies, had enemies all around them, and had to build from a zero point which these people would not have to do. $\endgroup$
    – Durakken
    Oct 1, 2016 at 3:30

Well. if they are a common medieval county they should have their grain transported with them. It seems to me that the time travel thing would pick up anything human built/manipulated and as such grains and at least cows would come back with them. They'd likely have enough grain to last them up to 8 years.

Let's assume they're English and as such are always going to be either on English soil of French soil, or near enough...let's also make this easy and say they're from 1000 CE, smack dab in the middle of the Medieval period.

The first period we look at is the 1 CE. Do they survive?
Supposing that that they are far enough in they should last a few generations and maybe till present day if they are all the way to the North, but too far south and they'll survive only between 30 and 200 years as their own place due to Roman invasion. I bank on the Romans winning even with better fortifications than those surrounding them, that just makes them a larger target. Other than that they should easily be able to continue living as they were. They would have to learn older languages and build up alliances for whatever, but other than that they'd be fine.

The next period we'll jump to is 11,000 BCE.
Depending on how bad the Late Glacial Maximum really was and how far it extended, them getting put here, they'd be dead within a few months more than likely, or be perfectly capable of survive. The largest issues they would face once they fixed their shelters to be more warm is setting up farm land which at this point in history Europe was more or less unsuitable for it, and mining which would only really take time and you can assume some village should have mining equipment and be right over some place they can mine so that isn't so much an issue. If farming failed there should still be plenty of large game in the area and Medieval humans should be able to easily over power most of them in that region.

100,000 years ago... They'd be dead very shortly due to the ice age.

1,000,000 years ago...
We're talking about a situation much like the 11,000 BCE one. There aren't many issues. There is evidence of Human in england in this period so assuming they have their grain stock or are able to find game animals, which they sould be able to there isn't a problem here.

10,000,000 years ago and beyond...
At some point the issue isn't the base ability to survive against the elements, but rather that the animals become just to fierce to handle. Humans lived with Terrorbirds and Mega-Mammalian Fauna. The Latter we know wouldn't be problematic, but the terrorbirds would likely tear humans apart, armored or not, especially with the armor that our humans would have. Keep going further back and the greater the likelihood of running to something horific that just can't be survived against up until just before the extinction of the dinosaurs which is harder to survive during due to the environment and all the animals going extinct. That seems to be the limit in my mind about how far back in time humans could reasonably survive from that period of time... Before that time period it's nightmare after nightmare in the fauna and floura.

We're talking animals that today kill us in a single sting or are pests or annoy us with bites and are just a few inches long at most... Now scale those up to a meter or 2. Or look in the ocean and find things that make great white sharks look like guppies. Every time period before this point has some crazy issue.

There is a period that I forget it's name that humans might have a chance in which is the period when mammal like reptiles were around, but I'm not too sure about that. But if we're looking the earliest time period humans can possibly survive in then it maybe be that. Dinos are the next level to them, but I highly doubt medieval warriors could handle most dinos.

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    $\begingroup$ You don't need to be able to fight an animal to drive it to extinction. You just need to out-compete it by hunting the same food source. Humans have driven many apex predators to extinction that could easily have won in a one on one fight. Saber toothed tigers, haast's eagle, etc. $\endgroup$ Oct 1, 2016 at 3:48
  • $\begingroup$ Are you talking modern humans in England 1Ma ago? If so - no. See en.m.wikipedia.org/wiki/Prehistoric_Britain. Certainly H. Heidelbergensis, but how much challenge would they be? Wait, there's a plot point. $\endgroup$
    – pHred
    Apr 15, 2019 at 4:07

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