Imagine there is a planet, which is populated by two entirely different intelligent species (though they may have some very distant common ancestor), but they are isolated from each other by some impassable by any simple means obstacle – imagine something along the lines of a huge unclimbable mountain range circling the Earth through the Pacific and Atlantic oceans – anything that could have prevented them from interacting and even knowing of each other. Of course, while they can't reach each other via ships, there is nothing to stop the airplanes, satellites, etc., but that's definitely requires very long scientific progress.

The urge for knowledge is impossible to hold back: the civilizations are at the level of about the middle of ours 20th century and one 'nation' accidentally stumbles upon another, very, very different from them – via the aforementioned satellites, maybe. Assuming that by that time people are smarter than in Columbus' times and that both civilizations have about the same level of technology so that one cannot easily conquer another – what could happen? To make the question more focused: is there a chance for a peaceful cooperation, or would xenophobic thoughts be too powerful? Assume that both species psychology is similar to ours, of course, for at least some chance of predictability.

UPD: As it turns out, my English is not as good as I thought, so to make it clear: I'm talking about the world where two civilizations are separated by something, which is impossible to get over without modern technology.

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    $\begingroup$ I think there's plenty of human history on this planet that would parallel that scenario. Europe vs. The Americas would be a good start. $\endgroup$
    – DA.
    Apr 2, 2015 at 21:18
  • $\begingroup$ @DA. Except the whole conquering part :) $\endgroup$
    – Samuel
    Apr 2, 2015 at 21:29
  • $\begingroup$ This is actually a brain twister. The moment we have the means to go somewhere, we will. Human history right there. So you wouldn't have a "all-of-a-sudden-doors-opened" scenario. You'd have prior communications, knowledge of each others existence, etc.. etc.. Unless these two civilizations are very different from us and somehow have no incentive to explore whatsoever, which would limit their growth immensely and make it that much harder for them to have ever reached the same level of technology etc... this is complicated : ( $\endgroup$ Apr 2, 2015 at 21:35
  • $\begingroup$ In all honesty the conquering will likely happen, perhaps not as direct or blatantly as in the new world. However, the two sides will see each other as alien and thus less 'deserving' of their land as we are. If you have a power disparity you get the Americas story. If both sides are truly equal to each other in might (unlikely) your get something closer to the cold war. I wish a more positive answer existed, but sadly humanity as a whole would respond to a rival species with fight or flight mentality. $\endgroup$
    – dsollen
    Apr 2, 2015 at 21:38
  • $\begingroup$ @Spacemonkey The thing is – they are physically isolated: no communications, no knowledge, not a single way to find out what's going on behind that obstacle – for all they know, there can be an ocean, spanning the entire hemisphere. Pretty much like our maps looked like before the whole 'exploring' thing: 'Here is our land, and around is... well... nothing' $\endgroup$
    – user8482
    Apr 2, 2015 at 21:42

4 Answers 4


At the equator an mountain range ringed the planet. The lowest pass was over 30,000 feet. While the existence of another hemisphere had been postulated for centuries, it could not be confirmed. Even with the invention of air travel, the prop planes could not be controlled as they approached the mountains due to the extremely powerful updrafts and constant thunderstorms on the slopes of the range.

For ages past, skeletons, well preserved corpses, and the occasional insane, haggard man were found on the slopes of the mountains. It was postulated that there were villages high in the mountains, filled with strange creatures. Those who found them often died of strange and painful diseases, and in Medieval times armies were sent to locate and destroy the source of the plague. Every decade or so, explorers attempted to climb the mountains. Few expeditions returned, and those who failed and came back often returned only to be sent to asylums, reduced to vegetables by hypoxia and cerebral edema. Bulky air tanks and other supplies were destroyed in freak accidents - but expeditions continued.

Mines were established in the mountains to locate rare metals needed for industry. These were used as refueling stations for the explorers as the deep mines had more air than the surrounding area. Some attempts were made to tunnel through the mountain, but miles of tunnels were met with no sign of an end, and the rapid geological changes caused frequent cave ins. Measurements of seismic activity suggested that the mountains did end (it wasn't all a plateau), but more than 200 miles of tunnel would be needed to reach the other side.

The first contact had been accidental. It was inexplicable interference on the wireless telegraph - at first attributed to atmospheric perturbations, and later determined to have a pattern. It took decades to establish 2 way communication because of the intense lightning storms in the vicinity of the mountains - eventually, it was determined to use a series of repeaters around the planet to bounce messages off of the upper atmosphere at sunset. Over time, both sides learned the others' language, and departments were set up in governments on both sides to establish relations with "the other side." Treaties led to information sharing to help the unseen allies, and wars one side led to diplomatic actions and even open fighting (see the French and Indian War in our own world).

The discovery that there was habitable land on the other side of the mountains, and that it was habited by people similar to them led to an immediate race for allies. A complex information-sharing system developed, where allies would research projects together and use espionage to tip the balance of power. A highly efficient technical pidgin developed, using simple electromagnetic pulses to encode information for allies on the other side. Doctors looked at schematics of devices sent across and determined that those on the other side were the strange mountain creatures of old.

[... Stuff happens ...]

Someone managed to develop a proxy to link the two internets. Super nerds developed the stack and began to form professional relationships. Facebook adapted easily, as most relationships were between people who had never met anyway...

[... more stuff ...]

Eventually it was determined that technologies had advanced enough to allow representatives of the two sides to meet in relative safety. It had been put off until the mid 21st Century (relatively speaking of course) because scientists were aware of the health risks of contact with such an alien species. The governments of two of the leading powers on each side determined to send a representative in space flight on a one-way trip to the other side, to become a permanent ambassador. This was scheduled to take place on the solstice, and the ambassadors would be monitored carefully by medical staff to determine what further contact was possible.

While perfect peace was impossible, the fragmented nations of both sides meant that local wars kept the peoples fighting those of their own kind, with technical assistance to allies on the other side. The ability to move any kind of fighting force across the divide would not be developed until manned space flight became cost effective. By that time, both sides possessed the technology to easily eliminate each other, so peace was the general rule.

  • $\begingroup$ That is definitely quite great, definitely worth of +1, though it's not exactly what I asked about. In your scenario, they cannot reach each other until quite distant future, and therefore, have no real possibility of war. In my scenario, though, it should definitely be possible to send troops and vehicles and so on via airplanes, so the war becomes a real thing. Anyway, once again: it's quite great, and the way you expanded my idea of mountain range is actually very awesome $\endgroup$
    – user8482
    Apr 5, 2015 at 20:15

I believe that in the situation you described, hostility is inevitable and it will probably lead to war. There are several reasons why.


Because these two civilizations were apart for so long, there are going to be a lot of differences.


Odds are, they can't speak the same language. Because of this, they will have trouble communicating, so it would be virtually impossible to form a peace contract. And if you can't have peace, then you must wage war.


Religion has been the cause of many wars. These civilizations will believe in different gods, or one might not even have any gods. Once again, this is reason to fight.


Living in completely different places will definitely make people evolve differently. They will look different. One might be taller, which is a reason to dominate. There is also the racial factor. For hundreds of years, white people kept black people as slaves. Slavery would probably happen after the war


Both of these civilizations are in the mid 20th century technology wise. From 1950-2015 there has been so many technological advancements. From the time that the civilizations are in now to where we are today, odds are one civilizations will be smarter then the other and develop faster. The more intelligent civilization will feel that they are better than the other civilization. They will also be able to overtake the other civilization because they are indeed better.


People always want power. There will be power hungry leaders on both sides. They will want the land and resources that they don't have yet. Odds are one civilization has access to resources that the other one doesn't and once they see that, they will want it. Also, the civilization will want to double their land by taking over the other side of the planet.

Overall, war is imminent. It's impossible for it not to happen.

  • $\begingroup$ You have some great points, but I don't think it would be very hard to make contact: bots sides have great linguists and the like, and the language may be not that completely alien: what if they do have common ancestor, they speak just variations of that ancient language? For the intelligence bit – I have mentioned that we assume (unlikely, but possible) situation, where they are equal, or at least balanced And the land thing – that's definitely not thad bad. You sure won't say that this is not like that in our world, and yet, we still don't have one great ruler, who have conquered everyone $\endgroup$
    – user8482
    Apr 5, 2015 at 21:02
  • $\begingroup$ @Akiiino Iceland and Danish was more or less, the same language about 1000 years ago. You can still tell that they share a common ancestry but most danes wouldn't be able to understand any icelandic. Almost all languages spoken in Europe belong to the Indo-European languages, much like Hindu -- I speak Danish, English, understand Norwegian, Swedish, some German, Icelandic, a bit of Dutch, Faeroesian, Spanish, French and a few words in most other Latin languages, but I have no idea what anyone is saying if they speak Hindu. Most Danes don't even understand other danish dialects. $\endgroup$
    – Clearer
    Dec 7, 2017 at 12:48

I think, if technologies were about equal, you'd need to think about the nature of both worlds. How did they form, what are their beliefs, what were their natures, what are their needs. Is a hemisphere one empire or split into many smaller, more divisive nations? Are there advantages to be had by trade?

I imagine that the interaction would begin with attempts at communication. Both sides checking out the other, some people generally curious and wanting to learn more about the other. Once more information is gathered - about the other sides society, structure, resources, weapons and vulnerabilities and intentions - leaders will make the decision on how they want to proceed. If they do decide war, it would probably not end in complete extinction (it hasn't yet).

It would be very cool actually if one side was very aggressive, an empire built on conquering all others. When the second world opened up it seems like a juicy new conquest, a peaceful nation with no military and beautiful verdant land. The empire invades, only to find that the new world has far more advanced weaponry and are able smack the empire down like a fly.


Not much really

For a while at least, there's not going to happen a lot. Mounting an expedition to meet the other people would be the first step -- one that would likely be easier to do via space crafts than using airplanes, i.e. it's going to be very expensive to do, and it's not likely anyone is going to send an army across that way.

Long term things could go any way. The two sections of the planet will likely have evolved quite differently and both sides will likely find it difficult to survive in the alien region; this means both sides will not be likely to attempt to colonize the alien region and have little interest in conquering the other.

Unless the people are able to interbreed they have very little reason to visit each other. The resources that could be exchanged would be easier to move without manned vehicles, or using vehicles that require very little manpower -- most likely the most traded commondity would be information in some form (tv-shows, books, software, research data, political ideas, history, religious beliefs etc.), and not hard matter (which is very hard to transport across the mountains/into space).

The most likely outcome, long and short term, is an acceleration in technology related to information exchange, space travel and tunnelling. The social effects will depend on the species on either region but I think all out war of any kind is out of the question -- it's simply too hard to do.


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