The ancestors of the Pawnee inhabited the plains region of North America since at least A.D. 1100 and migrated to the Region of the Loup, Platte and Republican rivers from a Southeasterly direction sometime prior to European contact. Contact with Spanish explorers may have occurred as early as 1541, but direct and sustained contact with Europeans did not come until the eighteenth century. During the contact period the native groups neighboring the Pawnee included the Arapaho and Teton to the west, the Ponca to the north, the Omaha, Oto, and Kansa to the east, and the Kiowa to the south. In 1803 the Pawnee territory passed under the control of the U.S. government through the Louisiana Purchase. In a series of treaties between 1833 and 1876 the Pawnee ceded their lands to the federal government and in 1874-1876 removed to Indian Territory. The gradual ceding of territory to the United States was done reluctantly, but out of necessity as White migration, depletion of the bison herds, and warfare on the plains between native peoples made it increasingly difficult for the Pawnee to carry on the hunting and farming way of life in their traditional territory. In 1870 the Pawnee split over the question of resettlement, but the issue was decided when they were forced to seek the protection of federal authorities after a massacre of Pawnee by the Dakota in 1873. In 1892 their reservation lands were allotted on an individual basis and the Pawnee became citizens of the United States. The transition to individual land ownership proved difficult, as the Pawnee tradition of village living proved inconsistent with individual farming.