Who made up the “Five Civilized Tribes”?

Five Civilized Tribes, term that has been utilized authoritatively and informally since at any rate 1866 to assign the Cherokee, Choctaw, Chickasaw, Creek, and Seminole Indians in Oklahoma (previous Indian Territory).

Explanation:

Five Civilized Tribes, term that has been used officially and unofficially since at least 1866 to designate the Cherokee, Choctaw, Chickasaw, Creek, and Seminole Indians in Oklahoma former Indian Territory. The term "Five Civilized Tribes" came into use during the mid-nineteenth century to refer to the Cherokee, Choctaw, Chickasaw, Creek, and Seminole nations.  Americans, and sometimes American Indians, called the five Southeastern nations "civilized" because they appeared to be assimilating to Anglo-American norms.

Explanation: