58 million years ago, horses first appeared in Central North America. 20 million years ago, grasslands flourished in Central North America. Therefore, horses also flourished. 10 million years ago, horses began to migrate across the Bering Strait, and numbers began to dwindle in the North American region. 10 thousand years ago, horses disappeared from North America. In the fifteen-hundreds, horses were re-introduced to North America by Spaniards.