The Dakota moved from northern Minnesota into the Great Plains in 1640. They went as far west as the Rocky Mountains. It was more or less at that time that they adopted horses as a mean of transport, to hunt buffalo and to be used in battle. The tribes who settled near the Rocky Mountains are known as Assiniboine and those of the Great Plains as Sioux Dakota. Both groups spoke Siouan.
The Chippewa/Ojibwa who lived in the upper Great Lakes region were pushed west by the colonial expansion of the French and the English as well as by the Iroquois. The Ojibwa invaded Sioux territory in Minnesota and the Sioux migrated west to the Plains. There they adopted the buffalo-hunting horse culture for which they are well known although before they had been a settled horticultural people living in the woods of Minnesota. During this migration process they broke into three groups speaking different but related dialects: the Santee, Yankton and Teton. The Santee remained agricultural people in Minnesota; the Yankton moved west to the Dakotas and combined agriculture with hunting; the Teton moved into the Upper Plains of Montana and the Dakotas. These last Sioux were great fighters, wanderers and buffalo hunters. They had seven sub-groups: Hunkpapa, Two Kettle, Sans Arc, Blackfoot, Miniconjou, Oglala and Brulé. The last two were the best tribes and were at the centre of the Wars on the northern Plains in the 1,800s.
Starting around 1700, many of the tribes that acquired horses migrated to the Plains. This was especially the case of the Commanches (southern Plains) and the Siouan-speaking people of Minnesota (northern Plains).
By 1760 all the Plains nations had horses and this changed their life. It makes buffalo hunting easier, it changed the rules of war and improved transportation of people and goods. Home ownership became a symbol of prestige and wealth.