The Sioux, one of the largest Indian nations in North America, divides into three large linguistic groups: the Dakota, the Lakota, and the Nakota. All originally came from Canada and were pushed westward as white settlements displaced other tribes along the eastern seaboard. They arrived on the northern plains comparatively late, around 1800, when they settled in the Dakotas, southern Saskatchewan, and eastern Montana. They were regarded as a noble but fearsome people, skilled in battle and famed hunters of buffalo.
The Yanktonai Sioux settled around Fort Peck, and along with some Assiniboin kinsmen, became residents of that reservation when it was created in 1888. Today almost 10,000 individuals belong to the tribe.
© W.C. McRae & Judy Jewell from Moon Montana, 7th Edition