Bison live there, the people are intruders.
Correction, Bison are kept there and are only allowed to roam certain areas. If they were allowed to roam where they wanted they would roam as far as into Canada down into Mexico, as far as Utah and almost to the East Coast. Suffice it to say Bison roamed around 80 to 90 percent of the North American Continent. And there are two types of North American Bison, tree and plains Bison.
This reminds me of the story, of how the American Buffalo are really bison, and not really buffaloes. I recall learning in school about that, but don’t remember the distinction between buffalo and bison.