The Fort Laramie Treaty of 1851 was signed on September 17, 1851 between United States treaty commissioners and representatives of the Cheyenne, Sioux, Arapaho, Crow, Assiniboine, Mandan, Hidatsa, and Arikara Nations. Also known as Horse Creek Treaty, the treaty set forth traditional territorial claims of the tribes.

The Cheyenne are an Indigenous people of the Great Plains. Their Cheyenne language belongs to the Algonquian language family. Today, the Cheyenne people are split into two federally recognized nations: the Southern Cheyenne, who are enrolled in the Cheyenne and Arapaho Tribes in Oklahoma, and the Northern Cheyenne, who are enrolled in the Northern Cheyenne Tribe of the Northern Cheyenne Indian Reservation in Montana.