The people of the Standing Rock Sioux Tribal Nation are often called Sioux. They are the members of the Dakota and Lakota Nations. “Dakota” and “Lakota” mean “friend” or “allies”. The term “Sioux”, dates back to the seventeenth century when some of the Dakota people were living in the Great Lakes area. The Ojibwa or Annishinaabe called the Lakota and Dakota “Nadouwesou” meaning “adders” or “little snakes”. This term was then shortened and corrupted by French traders, resulted in retention of the last syllable as “Sioux.”

The Dakota and Nakota people of Standing Rock include the Upper Yanktonai (in their language called Ihanktonwana, which translates to “little end villages”) and Yanktonai from the Cut Head Band. The Cut Heads, whose name is literally translated, get their title from the fact that when they withdrew from the Yanktonais, there was a row over secession and a fight. Their leader sustained a scalp wound and the name Cut Head was given. The Yankton and Yanktonais are called the Wiceyala or Middle Sioux. When the Middle Sioux moved onto the prairie, they had contact with the semisedentary riverine tribes such as the Mandan, Hidatsa and Arikara. Eventually the Yanktonai displaced these tribes and forced them upstream. However, periodically the Yanktonai did engage in trade with these tribes and eventually some bands adopted the earth lodge, bullboats and horticultural techniques of these people, though buffalo remained their primary food sources. The Yanktonai also maintained aspects of their former Woodland lifestyle. Today Yanktonai people of Standing Rock live primarily in communities on the North Dakota portion of the reservation.

The Lakota, as the largest division of the nation, are subdivided into the Oceti Sakowin or Seven Council Fires. The Lakota people of the Standing Rock Reservation included two of these subdivisions, the Hunkpapa, means “campers at the Horn” and Sihasapa or “Blackfeet,” not to be confused with the Algonquian Blackfeet of Montana and Canada, which are an entirely different group. The Hunkpapas get their name from their hereditary right of pitching their tepees at the outer edge of the village as defenders of the camp. The Sihasapa name comes from walking across a burned prairie after an unsuccessful expedition and their feet blackened, thus they were called the Blackfeet. The Lakota Hunkpapas and Sihasapa are the northern plains people and practically divested themselves of all woodland traits of their Dakota ancestors. The culture revolved around the horse and buffalo; the people were nomadic and lived in hide tepees year round. Their Hunkpapas and Sihasapa ranged in the area between the Cheyenne River and Heart Rivers to the south and north and between the Missouri River on the east and Tongue River to the west.