In pre-Columbian times, people of the Caddoan Mississippian culture occupied areas just to the north of the Big Thicket region. The Atakapa-Ishak (including the subgroups Akiosa, Akokisas, Bidai, Deadoses, and Patiri) occupied the Big Thicket area, living nomadically along the Gulf of Mexico in Southeast Texas and southwest Louisiana. They left evidence of hunting camps and such, although the Big Thicket area itself does not appear to have been the site of any significant permanent settlements comparable to the Caddo mound builders to the north. The Atakapa-Ishak speaking people were largely decimated by European diseases in the late eighteenth century, with only a few decedents surviving today. About the same time as the collapse of the Atakapa-Ishak people, the Alabama-Coushatta, originally two closely associated tribes living in adjacent areas of Alabama, began a westward migration about 1763 due to the encroachment of Europeans. The Alabama-Coushatta settled into the northern sections of the Big Thicket area by 1780, prior to the acquisition of their reservation in 1854.