The eloquent Eli Roth:

So when we shot it, I wanted to film somewhere that was really, really, really in the Amazon. Really, authentically off the grid. We scouted in the summer-time and went up the river for hours and hours and found this village where there was no electricity, no running water, grass huts. Ten people in a shack. And it looked incredible; it looked like a village from another time, so we asked if we could film there. But I was told that we have to tell them what a movie is because they have no idea. They’ve never seen one. They’ve never even seen a television. So they went back with a television and a generator and showed the village Cannibal Holocaust, which I couldn’t believe. And the villagers – thank god – thought it was a comedy. The funniest thing that they’d ever seen. And they wanted to play cannibals in the movie. So we had the entire village acting in the film. And they speak Quechua – which is like another language from another time.

Bullshit. Only the very few peoples who choose to have absolutely no contact with outside society wouldn't know what a movie is (and even some of them might have seen one, actually). I have watched DVDs hooked up to generators in many remote Amazonian communities. This is Mr. Roth's white man fantasy of "primitive tribes" which reduces indigenous people to silly stereotypes.

And don't get me started on "Quechua ... like another language from another time." Quechua in a highland Andean language and was only introduced to the Amazon later, so it does not have a very long history where they were filming. Different types of Quechua are currently spoken by millions of people in South America, and it is not any older or younger than English. Languages change gradually and aside from a few rare exceptions (i.e. newly formed sign languages) there is no good way to compare their ages or when they originated.

Roth's ignorance about the society he was filming is pretty pathetic, and leans towards racism. He wants to present a story about how they went to the most remote area and filmed with the most primitive people, but it is pretty clear that he had no idea what was going on around him in the local society.

Tl;dr: If you know anything about the Amazon at all, it is clear that everything Roth said about the place he filmed is bullshit he made up to sound cool.