Prior to 1640, the state of Illinois including both sides of the Mississippi River from Prairie du Chien, Wisconsin to the mouth of the Ohio, and then south along the west bank to the Arkansas River. The dominant tribe in the region before 1655, their hunting territory extended into western Kentucky and across Missouri and Iowa, the latter provoking occasional skirmishes with the Pawnee and Wichita on the plains (from whom the Illini learned the calumet ceremony). The Osage migration to the lower Missouri River (sometime between 1450 and 1650) isolated the Michigamea and Chepoussa from the other Illini.