Horses were in the Americas but went extinct before Europeans reintroduced them. There is significant oral tradition that remembers the importance of horses. How long ago the extinction of horses happened is hotly debated between white and native academics and likely varied widely depending on what part of the Americas you are studying. Scientists keep discovering horse bones that are radiologically dated to more and more recent times. The "official" extinction date has been revised down several times in the last few decades. There is even one highly debated sample that puts the date as little as 1500 years ago. Some native academics are working on genetic testing of wild horses in an attempt to prove American horses never went totally extinct at all.

I was writing a fantasy story with a Cree friend of mine that included realistic representation of Native American culture. We did extensive research to incorporate elements of the Cree, Haudenoshone, and Tlingit mythology and culture derived specifically from non-white sources. I don't have a doctorate or anything, but I know what I'm talking about.