Bison have not always lived in North America. They are relative newcomers. They belong to the Bovidae family, like domestic cattle and the wild buffalo of Africa and Asia. The oldest known bison fossils have been found in China and Himalayan foothills, where an animal with all the essential features of the genus lived a million years ago. They evolved rapidly and spread over most of the northern hemisphere in Europe and Siberia. During one of the Ice Ages, the faunas of Asia and North America began to intermingle. Very early, the steppe bison moved eastward to the North American continent. Much later, men followed the same route.