Question: Which federally recognized Native American nation that Island Bayou was a dividing line, and is one of the members of the Five Civilized Tribes?
Sentence (from "Chickasaw Nation"): Their removal was part of a larger effort by the federal government to relocate Native American peoples from the eastern side of the Mississippi River; in the Southeast, these were the Cherokee, Muscogee (Creek), Seminole, Chickasaw, and Choctaw nations.
Relevant evidence: No