Fiction by Jim Fergus.
This is a historical novel with a bit of a far-fetched premise: Chief Little Wolf of the Cheyenne tribe visited President Ulysses S. Grant in 1873 (true) to ask for one thousand white women (what?) to come to teach his tribesmen the ways of white people, and to marry into the tribe and produce children, of course (not true). Even more far-fetched is the next step: President Grant agrees to this and sets a government program in place to send white (and, incidentally, black) brides out West, using women desperate enough to volunteer for this (definitely not true).
As long as you can willingly suspend your disbelief on this initial idea and go with it, this is a great book. It definitely kept my attention and took a fantastical what-if to a logical conclusion.
But of course, it is not in any way historical fact. That's why they call it fiction...