In a pretty fascinating story yesterday, a group called Survival International released aerial photography of an "uncontacted tribe" of indigenous people's living in the Amazon jungle. The group is an advocacy organization on behalf of isolated tribal peoples and they say "We did the overflight to show their houses, to show they are there, to show they exist."
And, indeed, I had no idea that any such groups existed until I saw these stories. But there are around 100 such groups in the world, with about half of them living in Brazil, then another large group in the western half of New Guinea, and then the rest living in other parts of the Amazon. You can learn more here. The tribes face dispossession from the usual suspects for deforestation, but are also extremely vulnerable to epidemic disease.
Research indicates that "primitive" hunter gatherers actually enjoy a higher average standard of living than have most people in historical times and, indeed, higher than in many of today's poor countries. Agricultural techniques allow a given piece of land to support a much larger population, but at a lower standard of living.