Before the advent of satellite imaging, what would have been the easiest place to hide a secret civilization?

Question

Imagine that you're an adventurer archaeologist in the early to mid-20th century, like Indiana Jones. One day you find a lost civilization in an underexplored corner of the world. However, instead of abandoned ruins and booby-trapped temples of doom, you find a living society with a unique culture. It's like a mini-country which has somehow remained isolated from other civilizations for centuries. How plausible would such a situation have been given what we knew at the time? And where in the world could I put this civilization so as best to justify it going unnoticed by the rest of the world for so long? Please note that I'm asking for specific real-life regions and locations and that the civilization's technology level could range anywhere from Neolithic to early modern. Thank you.

Edit: The civilization doesn't have to be thriving, just doing relatively well. And it's okay if local people know about it and even trade with it, as long as they themselves are relatively isolated and low-tech and don't use written records.

Answer 1

Oh, any number of places.

The first possibility that comes to mind, which theoretically may actually hide isolated tribes in real life, are the various plateaus in the Amazon Rain Forest. Pretty much all of them are completely covered by trees, and they're largely inaccessible to humans even with modern technology because you have to hike through many miles of dangerous rain-forest just to get to them, all while carrying the required gear to climb up (because nobody wants to deal with the huge international stigma that would arise from using a Skycrane to get there by air and then use a daisy cutter to prep a landing zone).

The reality is that lots of other parts of the world are also pretty much completely unobserved by people most of the time, even with satellite imaging. That's part of why we can't conclusively refute some claims made by cryptozooligists, we just can't observe the areas in question well enough to conclusively say that there's nothing there.

The tricky part of this is to ensure that any 'locals' who are not part of this civilization don't discover it. Quite a few 'newly discovered' animals over the past century are cases where humans did in fact know about them, but nobody was willing to believe the locals. This is demonstrably the case with the giant panda, okapi, pygmy hippopotamus, and many other animals that many western scientists believed were too 'fantastical' to be real and thus must be legends.

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Additions in response to updates to the question:

If you don't care that any locals who are not part of the civilization know about them and possibly even trade with them as long as they are themselves isolated from the rest of the world, then this actually doesn't change much. It opens up only a few other parts of the world where there are native human populations that are still out of primary contact with the rest of the world.

As of right now (I can't find good historical data that indicates that the situation would have been different to a significant degree in the early to mid 20th century), the currently known but isolated and uncontacted tribes in the world are:

• The Sentinelese people, indigenous to Northern Sentinel Island (part of the Andaman Islands in the bay of Bengal). There have been sporadic instances of contact since the first recorded contact in 1867, but almost all have been either hostile or at best non-friendly, and the island is largely unexplored by outsiders. Currently, the island itself is functionally a fully autonomous self-governed protectorate of India with travel there strictly forbidden with an exclusion zone surrounding the island to a distance of five nautical miles (about 9.3km), though the Sentinelese likely do not know this. At about 60 square kilometers, the Island is small enough that it's not likely to hide an undiscovered civilization, but it's also covered entirely in forestland other than the beaches, so it's conceivable that there's something there that we don't know about.
• An assortment of about 50 uncontacted tribes throughout South America. Most such tribes have had only very limited contact with the rest of the world beyond other local tribes, and some are only attested based on information from other tribes in the area. Most such tribes aren't protected and are only uncontacted or isolated due to quite simply living really far from modern civilization.
• An assortment of about 40 uncontacted tribes in Western New Guinea. In these cases, most of them are today actively protected by law, but a lot of them were only (relatively recently) discovered.

Answer 2

New Guinea comes to mind as a real life example for a hidden post-hunter-gatherer civilization; from the Wikipedia article on the island:

Before about 1930, European maps showed the highlands as uninhabited forests. When first flown over by aircraft, numerous settlements with agricultural terraces and stockades were observed. The most startling discovery took place on 4 August 1938, when Richard Archbold discovered the Grand Valley of the Baliem River, which had 50,000 yet-undiscovered Stone Age farmers living in orderly villages. The people, known as the Dani, were the last society of its size to make first contact with the rest of the world.

The geography of the island made it specially inaccessible to (European) explorers until the advent of flight.

Answer 3

I will take your pre-satellite idea and take it one step further by hiding from those too with...

An Underground City

Matmata, in Tunisia was an underground community of over 2000 people that was not discovered by the local government until 1969 when flooding collapsed many of thier homes forcing them out of hiding. The people of Matmata stayed hidden most of the time, with locals believing that the region only contained a very small number of nomadic herdsmen; so, with just enough people to tend some flocks they were able to keep the existence of an entire permanent settlement a complete secret to the outside world for generations.

Part of what makes this so compelling is that it was not somewhere all that remote. Matmata had several towns within about 20 miles away from it to the north, east, and west. So, if you were to take this same concept and move it to somewhere that is actually remote, you could probably get away with hiding a much larger underground city more like Derinkuyu, Turkey which housed closer to 20,000 people.

Answer 4

LEMURIA! or, Islands, small places, culture, and will:

I think the best place to find an isolated culture in the mid-20th century would be a largish-sized island or possibly a valley deep in the mountains in a relatively isolated part of the world. Before WW2, there were a number of islands where there was no or virtually no contact with the outside world. People saw airplanes dropping goods to soldiers, and believed them to be gods bearing gifts, giving rise to Cargo cults. (the details of cargo cults are debated, but still...) If you have a complicating factor, like a sargasso surrounding it, this helps justify lack of exploration. The south pacific is about as isolated as you can get, but there were plenty of explorers who went there as well. You'll need additional factors to conceal a sizeable thriving civilization.

There are still places in the world where the locals have virtually no contact with the outside world, but often this is partly by choice. First, the locals need to have no desire to explore - hard to justify unless your culture is extremely insular. A religious or cultural practice emphasizing hostility towards strangers (hard on your explorer), purity of the sacred land/people (so anywhere else is not worth visiting), and lack of change (Amish on an island) can help explain why no one visits (and lives...) and no one leaves.

A stone-age society is easiest to justify, as most of the isolated groups today are at this level and these societies don't require complex inputs of resources to keep going. More sophisticated ones would need stronger isolation and practices to explain (like a kill all foreigners on sight policy). Otherwise, a society that isn't isolated for long (like victorian British colonists deliberately isolating themselves and someone deliberately erasing the memory of them from the history books) could be explainable. Your explorer could find an imperial map with Lemuria on it, but wait, there IS no Lemuria! Ah, but Queen Victoria wanted her wayward relatives (rivals to the throne?) sent away and then deliberately erased all references to the place so no one would ever find out...

Answer 5

A very remote corner of the world they could be hidden on is Antarctica, maybe an inland valley with enough hydrothermal activity to make it livable year round. Growing crops would be a problem with the limited sunlight, but not impossible to eek out an existence with good hunting/fishing available at the coast. Deception island has hot springs on it and lots of wildlife, plus as a very sheltered harbor, might hide a small civilization from outside observation from most directions.

Answer 6

Your thriving but hidden civilization needs 3 plausible things:

1. Isolation
2. Resources
3. Cultural pressures

Isolation would most likely be geographic, although a borderland, filled with super evil venomous monsters could do in a pinch. You probably also need an isolation event as well e.g.,

1. Storm blew colony ship off course
2. Zeplin crashed in remote lush valley
3. Landslide cuts off access route
4. Giant Spiders settle in the boarderlands
5. All of the villages in-between died out in a plauge (our village practiced physical distancing and hand washing, how quaint)

Resources, so Easter island is isolated, but lacks many resources. So you need some place with say lots of easily smeltable metal ore, and fertile land. So they can grow but be self sufficient within their bubble.

Cultural pressure, is probably the most important. You need something which causes the society to overcome, cooperate, specialize, trade (internally), and adapt. Examples of this are:

1. Climate in northern Europe.
2. Needing to create a bureaucracy to manage annual flooding of the Nile in bronze age Egypt

As to where...

It depends what you mean by thriving. There are plenty of pacific islands that are isolated. I would say they not thriving, but small (happy) and stable. They don't have many cultural challenges*. ( Because there is a consistent ready supply of resources (you can just just stick a few sticks of cassava in the ground and 6 months later you have a harvest) There is little need build up an excess and then use that excess to trade and level up.

I think if you look at map of the globe at night, anywhere there are not too many lights will make a good spot. Basically any where isolated. But it would need to be somewhere different than where the target audience lives. Even though New Zealand is the last place in the world (excluding Antarctica) to be settled; it would seem silly to me (I live in NZ) to frame it as where lost city of Atlantis was located. The same goes for Shangri-La if you come from Tibet or northern China.

You know, with a few carefully picked isolation events you could locate your civilization in Switzerland! Interesting and different culture, physically isolated on pretty much 3 sides. Add a plauge and some wolf's in the North, a couple of fires in some library's and council offices burning up records of their neighbors, bake for 100 years or so, and boom hidden civilization right in the middle of Europe!

*I don't want to seem like I am belittling the rich cultures of pacific islands. I just think OP is looking for a civilization with something like metalworking, large temple grounds, that kind of thing.

Answer 7

Easter Island

When European explorers arrived in 1722, the population of Easter Island was down to 2,000 to 3,000 people. Much earlier, there had been a much larger civilization on Easter Island and there had been ongoing trade exchanges with Polynesia.

But Polynesians had stopped going to Easter Island sometime before 1722. So it was, in effect, isolated.

Answer 8

An island, country or even continent in the middle of an ocean. Prevailing winds and currents could make it difficult for ships to approach or depart.