Originally settled in a land of forests and many lakes, presumed to be near what is now Lake Winnipeg, Canada, the ancestors of the Crow Nation began moving southwestward about 1550 A.D.  The group was composed of two bands, one of which subsisted by farming, the other by hunting.  Upon reaching the northeastern North Dakota area, the two bands paused.  During their stay in the Devils Lake area the medicine men called upon the Great Spirit for guidance in their travels.  The farmers were told to move farther westward until they found a land favorable for growing corn.  The hunters received a sacred tobacco seed from the Great Spirit and were told to travel farther westward until they came to a good land where the tobacco would grow and they would grow strong and wealthy.

Both bands pushed westward reaching the confluence of the Yellowstone and Missouri Rivers and at this point the two bands separated.  The farmers remained in this area but the hunters pressed westward reaching the Bow River of southwestern Alberta, Canada.  Because of the harsh winters the band traveled southward reaching a large lake of salt water, eventually reaching the headwaters of the Arkansas River and Red River.  Still looking for the right location for the growing of the sacred tobacco seed they continued northward, eventually reuniting with the horticultural band.  About 1750 the recombined tribe began to acquire horses when they divided into two factions with the hunters once again headed west.  Eventually, these hunter horsemen reached the Big Horn Mountains in what is now southwestern Montana and northern Wyoming. And finally, here it was that they planted the sacred tobacco seed on the eastern slopes of the Big Horns.  They settled into a nomadic hunting type of existence in contrast to the semisedentary life typical of the faction, known today as the Hidatsa, that stayed behind.  Even today similarities between the Hidatsa and the Crow languages reflect their past relationships.

The vast stretch of land lying between the Black Hills of South Dakota and the Rocky Mountains of Montana and Wyoming, and between the North Platte River in Wyoming and the Milk River in northern Montana, was regarded by the Crow as their hunting territory.  As pressures mounted from eastern tribes being pushed westward by European settlers, conflict arose over this prime hunting land.  The Crow were in constant conflict with the Blackfeet to the north and west, the Shoshoni and Arapaho to the south, the Nez Perce to the west, and the Cheyenne and Sioux from the east.

With the arrival of the US military the Crow took advantage of the superior forces and the protection they offered by aligning themselves with the military.  In response to their friendliness and helpfulness the Crow were treated as friends.  In the Fort Laramie Treaty of 1851 the Crow Tribe was assigned an area of over 38,000,000 acres in what is now northern Wyoming, southern Montana and western South Dakota.  This was agreeable to the Crow as it gave them possession of some of the best game country in North America.  With some friction arising over usage of the territory by gold seekers, other tribes and the US military, the terms of the second Treaty of Fort Laramie (1868) reduced the Crow Tribe lands to 9,000,000 acres.  After several more reductions in size, the Crow Reservation now encompasses approximately 2.3 million acres which include the northern end of the Big Horn Mountains.