Imagine, if you will, that beyond your towns and farms - the only world you know - dwell large settlements of aliens from outer space, of which you know very little, except that they are completely different, and incomprehensible. You see their flying saucers passing overhead, and more and more frequently they themselves are intruding into your domain. But you keep your distance, because oral tradition tells how they once committed terrible atrocities against your kind, or that once there were friendly relations, but then they brought the plague upon you.
This, essentially, is the experience of thousands of Indians who are literally hiding from the outside world in the fastness of the Amazon jungle. Every time it is announced that the last uncontacted tribe has been discovered, another turns up. But once there were millions of them - only to be wiped out by massacre and enslavement, but mostly, as in North America, by infectious diseases which could devastate whole communities before any white man arrived. And somewhere in this maelstrom of destruction there was lost a community which most people now relegate to mythology: the women warriors after which the Amazon River was named.