Chickasaw is a Western Muskogean language spoken by less than 75 people mainly in Oklahoma. All of the speakers are over the age of 55: the younger generation are drifting towards English. Despite the similarities between Choctaw and Chickasaw, most Choctaw speakers find the latter unintelligible.
During the 17th and 18th centuries Chickasaw was used as a lingua franca among all the tribes of the lower Mississippi river. The Chickasaw were one of the five Civilized Tribes forcibly removed to Indian Territory (now Oklahoma) in the 1830s. The other Civilized Tribes are the Cherokee, Choctaw, Creek and Seminole.
source
wikipedia.org,
omniglot.com &
ethnologue.com