white man evil

I think noone exactly denies that also Amerindians could be cruel and wage war to each other. Earlier in Euro American propaganda such teachings were actually quite common and mostly overly exaggerated. It was in the interest of the western society to try to rationalize its genocidal behaviour against Amerindian peoples.

Today many scholars take a more moderate approach to the subject and try to evaluate these things more objectively.

What one often forget in comparing intertribal warfare with the onslaught on the amerindians from western society, is that  the later in the long run were of a much greater scale, and its consequences were more profound. The western colonisation, warfare, massacres and genocidal activities had a much larger impact.

Combined with the diseases spread by the westerners it would have much greater effect on the Native American demographics. Entire tribes disappeared, entire cultures were destroyed. The Amerindians lost their land, got displaced, exterminated or forcefully assimilated on a scale that was unheard of before. The destruction reached a magnitude that was unprecedented.

Also one shall not forget that many conflicts among Amerindians escalated because of the pressure from the colonialists. The colonialists managed to divide and rule and create conflicts among the native groups. These groups were dragged into the conflicts between European powers or different sides in Euro American internal conflicts.

So even if there were conflicts and cruelties among Amerindian peoples, those conflicts are dwarfed by the brutal impact of European, western civilisation.