The Hidatsa originally lived in the Devils Lake region of North Dakota, before being pushed southwestward by the Lakota. As they migrated west, the Hidatsa came across the Mandan at the mouth of the Heart River. The two groups formed an alliance, and settled into an amiable division of territory along the area's rivers. Prior to the epidemic of 1782, they had few enemies. The Hidatsa hunted upstream from the earthlodge villages at and below the Knife River. Here, between the Knife and Yellowstone River, they were numerous enough to withstand attacks of the Assiniboine, who hunted in the area but rarely wintered on the Missouri River. Now as part of the mighty Iron Confederacy they were an opponent the Hidatsa had to pay attention to.A remarkable siege of the village Big Hidatsa by the Sioux around 1790 ended with a major victory for the inhabitants. They killed 100 or more retreating Sioux in a counter attack, according to the sources.

The Hidatsa played a central role in the Great Plains Indian trading networks based on an advantageous geographical position combined with a surplus from agriculture and craft. Historical sources show that the Hidatsa villages were visited by Cree, Assiniboine, Crow, Cheyenne, Arapaho, Kiowa, Plains Apache and Comanche. White traders from the north, like North West Company man David Thompson, began to visit the Hidatsa and Mandan villages during the 1790s.