The Chickasaw Nation (Chickasaw: Chikashsha I̠yaakni) is a federally recognized Indigenous nation with headquarters in Ada, Oklahoma, in the United States. The Chickasaw Nation descends from an Indigenous population historically located in the southeastern United States, including present-day northern Mississippi, northwestern Alabama, southwestern Kentucky, and western Tennessee. Today, the Chickasaw Nation is the 12th largest Indigenous nation in the United States, with a population exceeding 80,000 citizens, most of whom reside in Oklahoma.

The Chickasaw Nation’s reservation spans approximately 7,648 square miles in south-central Oklahoma. It is divided into four districts: Pontotoc, Pickens, Tishomingo, and Panola, which include counties such as Bryan, Carter, Coal, Garvin, Grady, Jefferson, Johnston, Love, McClain, Marshall, Murray, Pontotoc, and Stephens counties.

During the 18th and 19th centuries, several Indigenous nations, including the Chickasaw Nation, were noted for adopting centralized governments, written constitutions, and participating in agricultural economies. These nations, historically referred to as the Five Civilized Tribes, also engaged in cross-cultural exchanges, such as intermarriage and the integration of educational and religious practices, as part of their adaptive strategies to navigate changing political and social conditions.

The Chickasaw language (Chikashshanompa’) is part of the Muskogean language family. It is primarily an oral language, and much of the Chickasaw cultural heritage is preserved through intergenerational storytelling. The linguistic similarities between Chickasaw and Choctaw have led to various theories about their shared origins, though definitive conclusions remain uncertain.

The Chickasaw Nation’s societal structure is based on matrilineal clans, with two traditional moieties: the Imosak Chá'a' and the Inchokka' Lhipa'. Clan leaders hold significant roles in maintaining the cultural and organizational integrity of the nation.

Clans within the Chickasaw Nation are separated into two moieties: the Imosak Chá'a' and the Inchokka' Lhipa', with each clan having their own leaders. Their tradition of matrilineal descent provides the basic societal structure of the nation, with children becoming members of and under the care of their mother’s clan.

Mississippian cultures developed around 800 CE along the Mississippi River and across the Eastern Woodlands with some regional variations. This was a period of increasing sociopolitical complexity, with the intensification of agriculture, settlements in larger towns or chiefdoms, and the formation of strategic alliances to facilitate communication. Organization of labor is evidenced by mounds, and the skill and craftmanship of artisans is reflected in the elaborate and intricate remains of burials. Furthermore, as chiefdoms arose within the Chickasaw Nation—and across the Southeast in general—the increased social complexity and population growth were sustained by effective and widespread farming practices.

While the origins of the Chickasaw continue to remain uncertain, anthropologists and historians have proposed several theories. One theory is that the Chickasaw were at one time a part of the Choctaw and later branched off, given their close connections linguistically and geographically. Another is that they were descendants of the pre-historic Mississippian tribes, having migrated from the West given their oral histories. According to some of their oral stories, the Chickasaw first settled in the Chickasaw Old Fields, what is currently northern Alabama today, and later re-established themselves near the Tombigbee River.