Hnau
Banned
I propose a POD: one of the Incas pushes for trade with the Amazon River societies and the increased contact promotes more "civilization". One of the more isolated societies (best located probably on a tributary of either the Jurua or Purus Rivers) performs the strange feat of adapting quickly to what they've learned from the Incans and just as quickly changing all of the sudden (religious upheaval?) to become extremely xenophobic. They begin killing all outsiders on sight. When the European diseases show up, they also become highly effective at putting anyone showing symptoms straight to the sacrificial pyres.
The society that survives until the 20th century may be very small and very unlikable, but they might fit your criteria. They would probably have even less complex of a society than the Tawantinsuyu, because really, how much can you pick up in at most a 100 years, but that's the best you can get in my opinion.
The society that survives until the 20th century may be very small and very unlikable, but they might fit your criteria. They would probably have even less complex of a society than the Tawantinsuyu, because really, how much can you pick up in at most a 100 years, but that's the best you can get in my opinion.