More Information
It's a little know fact that most of the evolution of the horse actually occurred on the North American continent. From around 54 million to 10,000 years ago, horses were an extremely successful species. They were grazers that covered the Great Plains, but eventually spread out through many parts of the continent. At some point in time some horses managed to cross into Asia then Europe by means of the Arctic-Asia land bridge which existed during that time period. For some reason, possibly due to drought, disease or being overly hunted by both humans and other predators, horses vanished from North America. The submergence of the Bering Sea Bridge prevented horses from reappearing in North America until modern European man brought them back over on boat.
