Prior to the arrival of European explorers and fur traders in North Dakota, at least seven different groups of Native Americans lived in what is now North Dakota: the Assiniboine, Chippewa, Mandan, Hidatsa, Arikara, Cheyenne and Yanktonai (branch of the Dakota). The Cree also spent time in the area.

Although the Arikara, Hidatsa, and Mandan spoke different languages, observed different customs, and lived miles apart, there were numerous similarities in their buildings and farming methods. These three tribes, identified today as the Three Affiliated Tribes, lived in permanent earthen lodges along the Missouri River in central North Dakota. Primarily they were farmers who grew corn, sunflowers, pumpkins, beans, and squash. They hunted buffalo and other animals for extra food and also served as "middlemen" in trade between other Native Americans.

The Assiniboine called themselves Nakoda (the people) or Nakota (the generous ones) and were allies of the Cree. Their language is a dialect of Dakota and they were typically large game hunters and lived in hide tipis. The Dakota were their bitter enemies and they were considered quite warlike. They were predominantly located in the northeastern region of North Dakota and now reside across the border in Canada.

The Cheyenne were originally woodland dwellers, then semi-sedentary plant growers associated with the Mandan, Arikara and Hidatsa. Later they moved further west and developed into excellent horsemen and buffalo hunters, and became, for a while, a great warrior nation. They were very adaptable and inventive and eventually allied with the Dakota.

The Chippewa were originally forest dwellers, and the southern group eventually settled in the Turtle and Pembina mountain areas of northeastern North Dakota. The name Chippewa is the popular adaptation of Ojibway. As they moved westward they came into conflict with and defeated the Fox and Dakota who challenged them.

The Dakota are commonly known as Sioux or Dakota Sioux, but the correct name is Lakota, and the fuller name is Teton Lakota. The word Sioux is probably from the old Chippewa word for "enemies to the west." The Dakota were originally a great nation, having three dialects and seven major bands or council fires. To most non-Indians, the Dakota are the classic example of the Plains Indian warriors. Ironically, they were originally a shy forest people driven westward by the Chippewa. By the mid to late 1800s, after obtaining horses and guns, they became mighty warriors, driving out all tribes before them and earning the respect of the whites due to their mastery of military tactics and war.

The Cree were a huge, diverse band of hunters and occupied a large part of Canada and parts of extreme eastern North Dakota. They were friendly with the Chippewa, but fought the Iroquois and Dakota. The majority of the Cree now live on reservations in Manitoba, Canada.

After signing treaties with the United States government from the 1850s to the 1870s, North Dakota Native Americans were placed on several reservations. Many tribal members remain on these reservations still today. There are five reservations in North Dakota, two of which occupy land in both South and North Dakota. The Spirit Lake Nation (Devils Lake Sioux) is located at Devils Lake, in east central North Dakota. The Fort Berthold Reservation is home to the Three Affiliated Tribes (Arikara, Hidatsa, and Mandan), and lies in the west-central part of the state along the Missouri River. The Standing Rock Reservation (Standing Rock Sioux) straddles both North and South Dakota and is about forty miles south of Bismarck, North Dakota. The Turtle Mountain Reservation (Chippewa and Metis) is the northernmost reservation, just below Canada in north central North Dakota. The Sisseton Reservation (Sioux) is predominantly in South Dakota, with just the northernmost edge in southeastern North Dakota.