Twentieth-century scholars , such as the archeologist Patricia Galloway , theorize that the Chickasaw and Choctaw coalesced as distinct peoples in the 17th century from the remains of Plaquemine culture and other groups whose ancestors had lived in the Lower Mississippi Valley for thousands of years .
Twentieth-century scholars , such as the archeologist Patricia Galloway , think that the Chickasaw and Choctaw came from the Plaquemine culture and other groups whose ancestors had lived in the Lower Mississippi Valley for thousands of years . The Chickasaw and Choctaw then became distinct peoples in the 17th century .