Navajo believe that The People came into this, the fourth world, at the Place of Emergence in Northwest New Mexico, to escape a flood in the lower world. The boundary of the Navajo Nation today roughly follows the traditional boundary set by the Four Sacred Mountains. Modern theory describes the Navajo people as semi-nomadic. The early Navajo people subsisted on herding sheep and planted large fields of corn. They quickly adapted to the use of horses and other livestock introduced into the region by the Spanish.
The Sioux originally occupied the Great Lakes Region but migrated west to the Great Plains in the mid-1700s, when they acquired the horse; some didn’t migrate until well into the 1800s. The main body of migration was driven from their Minnesota homeland by the Chippewa. The Sioux in turn usurped much Crow territory. There are still some Sioux living around the Great Lakes.