The so-called "civilized" Europe has a brutal history of colonialism and I'm glad such documentaries are being made, for the posterity to know the truth. Just because the natives of South America were at war against each other, does it make it right for an obviously more technologically advanced society to have inflicted endless pain and suffering onto them? Europeans have never stopped inflicting barbarism and cruelty against each other, even to this day. The truth, while uncomfortable to many, has to be shown in its unadulterated form. That's what makes such works powerful, because they trigger a thought process, and this is precisely why we should not alter and rewrite when presenting it.