The Five Civilized Tribes were the five Native American nations: the Cherokee, Chickasaw, Choctaw, Creek, and Seminole, which were considered civilized by Anglo-European settlers during the colonial and early federal period because they adopted many of the colonists' customs and had generally good relations with their neighbors. Five Civilized Tribes lived in the Southeastern United States before
the government forced their relocation under Indian Removal to other parts of the country, especially the future state of Oklahoma. The tribes were relocated from their homes east of the Mississippi River over several decades during the series of removals, authorized by federal legislation. They moved to what was then called Indian Territory, now the eastern portion of the state of Oklahoma. The most infamous removal was the Cherokee Trail of Tears of 1838, when President Martin Van Buren enforced the highly contentious Treaty of New Echota with the Cherokee Nation to exchange their property for land out west. The Five Tribes were divided in politics during the American Civil War. The Choctaw and Chickasaw fought predominantly on the Confederate side. The Creek and Seminole supported the Union, while the Cherokee fought a civil war within their own nation between the majority Confederates and the minority, pro-Union men. Once the tribes had been relocated to Indian Territory, the United States government promised that their lands would be free of white settlement. Some settlers violated that with impunity, even before 1893, when the government opened the "Cherokee Strip" to outside settlement in the Oklahoma Land Run. In 1907, the Oklahoma Territory and the Indian Territory were merged to form the state of Oklahoma.