Robert A. Grom, The History of Badlands National Monument and the White River…
“ Around 1775 the Oglala and Brule, tribes of the Teton Sioux, moved west of the Missouri River to occupy respectively the Bad River country (around the present town of Philip, S.D.) and the region along the White River south of the Badlands. Because of their move from a timbered area to a plains region, the Sioux underwent great adjustment. As the result of acquiring guns from the whites and horses from other tribes, the Sioux became primarily a nomadic people, dependent on buffalo for sustenance. ”
