On January 29, 1861, Kansas was admitted to the Union as America was on the brink of Civil War. Four main tribes lived in eastern Kansas before white settlers arrived – the Kansa, Osage, Pawnee, and Wichita. After acquiring horses by the late 1700s, the Arapaho, Cheyenne, Comanche, Kiowa, and other tribes moved into the central plains to hunt buffalo.