The Caddo Nation is a confederacy of several Southeastern Native American tribes. Their ancestors historically inhabited much of what is now East Texas, Louisiana, and portions of southern Arkansas and Oklahoma. They were descendants of the Caddoan Mississippian culture that constructed huge earthwork mounds at several sites in this territory, beginning about 800 CE. In the early 19th century, Caddo people were forced to a reservation in Texas; they were removed to Indian Territory in 1859.