Wow. Where did you read this stuff?
As I recall, the bit about the bison drives came from a Time/Life book on the Native Americans, which I read in the 1970's (would be about 1978-1979). The part about the horses I read somewhere on the internet, about three years ago, although I cannot for the life of me recall which site I read that particular gem on...
the infowarrior
Horse extinction and reintroduction to North America by Cortez and his men.
Equus sp. ranged widely over North America at that the end of the Ice Age but became extinct in North America several thousand years ago. It is not known why they became extinct in North America. Horses were reintroduced into North America by the Spaniard Cortez in 1520