We like to differentiate between peoples as if one set were the bad guys and one set were the good guys. The truth is, is that whenever a more advanced culture encounters a less advanced culture, primarily displayed throughout human history with hunter gatherers encountering agriculturists, the less advanced culture always is overtaken in some manner. Some of the reasons the Americas were overwhelmed by Europeans, as outlined in the book "Guns Germs and Steel" are the following:Few domesticable work animals in the Americas, not a wide variety of high caloric yielding crops in America compared with Eurasia (only corn and a few others), Geological barriers disallowing civilizations to trade/share ideas with one another, primarily North-South axis of the continent making commerce of crops difficult due to the change in climate, lack of a writing system, disgust with those in power who would sacrifice a very large percentage of the population (primarily in the Aztec empire), no advanced system of writing to record historical events, lack of resistance to the European diseases (some estimates claim up to 95% of the indiginous population were wiped out). The trend in human history, regardless of what continent you look at, is that the more advanced civilizations conquer the weak. Both the Europeans and the native American peoples had things about their civilizations worthy of criticism, but it really isn't fair to criticize the Europeans because Lord knows the Americans would have colonized Europe just as fast given the opportunity,