Coles Creek culture is an archaeological culture in the Lower Mississippi valley in the southern United States. The period marks a significant change in the cultural history of the area. Population increased dramatically and there is strong evidence of a growing cultural and political complexity, especially by the end of the Coles Creek sequence. Although many of the classic traits of chiefdom societies aren't yet manifested, by 1000 C.E. the formation of simple elite polities had begun. Coles Creek sites are found in Arkansas, Louisiana, Oklahoma, Mississippi, and Texas. It is considered ancestral to the Plaquemine culture.