The Standing Rock Sioux Reservation can be found in the states of North Dakota and South Dakota. The people of the Standing Rock Sioux Reservation generally include the Upper and Lower Yanktonai. The Sioux people may have originally lived near the Great Lakes, but probably moved west onto the American prairies due to encroachment from other tribes and European settlers.
When the Standing Rock Sioux moved onto the prairie, they may have displaced some of the tribes living there at the time. These tribes may have included Hidatsa, Arikara and Mandan. The people of the Standing Rock Sioux belong to the Lakota and Dakota nations. Dakota and Lakota are the Sioux people's names for themselves, and mean "friends" or "allies." The term "Sioux" originated with French traders in the 17th century.
The Sioux are believed to have displaced the river-dwelling tribes who lived on the prairie before their arrival. The Sioux are believed to have maintained open trade relations with these tribes. Some Sioux communities may have adopted the technologies used by the tribes they displaced, including the earthlodge and bullboat. These Sioux tribes may have also taken advantage of the displaced tribes' agricultural techniques. The Dakota peoples of the Standing Rock Sioux are also generally believed to have retained some aspects of their traditional, forest-dwelling lifestyle and culture.
After the Sioux people left their traditional forest-dwelling lifestyle for a life on the prairies, they are believed to have begun relying primarily on buffalo as a food source. By the 19th century, many of the Lakota peoples of the Standing Rock Sioux are believed to have adopted a plains-dwelling lifestyle. Aspects of the traditional forest-dwelling Sioux culture are believed to be absent from the plains-dwelling culture of the Lakota Sioux. On the prairies, the Lakota Sioux are believed to have gradually developed a nomadic culture based on hunting large game such as the buffalo.
The Lakota people are considered more numerous than the Dakota people. The Lakotas of the Standing Rock Reservation include the Hunkpapas and the Lakota Blackfeet, a different tribe from the Algonquian Blackfeet of Montana and Canada. These peoples generally migrated further north than the Upper and Lower Yanktonai of the Dakota Sioux. They are believed to have created a distinct plains-dwelling culture away from the influence of other displaced tribes.