Mestizo is the term used.Yeah, though most are actually half-natives, don't know word in english, metis? Or are you talking about those tribes sitting really in the middle of the Amazon?
You know, it's sad in a way, though the Aztecs and the Mayans were kind of extremely violent, the Inca were a bit more rational, I read a bit about them, their empire could have rivaled those of our days with similar technology, they already had layed some aspects of an orderly society, taxing, redistribution of wealth, infrastructure, aqueducts etc.