Support this. Where are you pulling this from? Consider how diverse the various Native American tribes and nations were. Some were hunter-gatherer societies, following herds. Others were agricultural communities. And that's only in North America... let's not forget the Inca, Maya, and other South and Central American cultures.
What, by and large, the Native American tribes don't seem to have done is developed a structured or hierarchical means of passing on or recording their approaches to combat. One can be fairly confident that they did have something -- even if it was simply a variant of "this is where you shoot an arrow into a buffalo to kill it" a la "this is where to whack a guy in the head to kill him." The other thing is that European cultural imperatives did a wonderful job of crushing a lot of those traditions. I'm not aware of anyone teaching what they claim to be Native American martial arts that doesn't have a huge Eastern influence and pressure. Doesn't mean there are none out there... just that I haven't found one that I'm convinced of the legitimacy of lineage claims.
As to "the white man"... There is a lot of documentation of the various combative approaches in Historical European Martial Arts. Not sure where you're going with this.