You know this about the American Indians before the white man ever arrived. Tribes were always making wars on each other. But the idea that these wars were over the best hunting grounds, the best natural resources, access to water, is a myth.
Most wars were agitated for by the young braves. So that they could gain more honor and status (more sex partners) by being a brave, fearless and superior warrior/ And to capture the enemy tribes women to make them into sex-slaves, concubines, wives and baby factories. The tribe with the most people wins. The most male warriors will win.
This was their take on demographics.
You mean it wasn’t like in “Dances with Wolves?”