From a time when there were a million of them roaming across much of the continent, to a time when their numbers were reduced to two small herds in all of North America, the American buffalo went through bad times after the white man came to its part of the world. They were killed for sport, slaughtered. The efforts of the American Bison Society were instrumental in redirecting the bisons' future. In 1894 the U.S. Department of the Interior prohibited the killing of any more buffalo in Yellowstone National Park. Slowly the herds began to grow. The American buffalo is related to the aurochs of Europe, which also enjoy a protected status in Eastern European reserves.