Comprised of various groups with distinct dialects and customs, the people known today as the Caddo occupied a region that included parts of present Louisiana, Arkansas, Oklahoma, and Texas as early as A.D. 800. By the 16th century, they had developed complex, hierarchical societies with civic and ceremonial centers as well as advanced agricultural practices. Early Spanish and French accounts recorded the Caddo and their customs. Despite successful trade with Europeans, especially the French, the Caddo eventually faced a rapidly declining population because of exposure to Old World diseases and the arrival of other Native American groups from the eastern United States. Anglo-American settlement in Texas further threatened and limited the Caddo homeland, and by the late 1850s they were forced to relocate to Indian Territory, present Oklahoma. Today the Caddo Nation headquarters is in Binger, Oklahoma, where members maintain cultural traditions through pottery, song, dance, and language. As an ancestral homeland, the area drained by Cypress Creek remains an important part of Caddo heritage, and archeological research there has used records, artifacts, and landscape features to trace Caddo occupation from as early as A.D. 800 to 1680, including a period of contact with Europeans and Southeastern Indian groups and evidence from pottery styles, mound construction, cemetery types, and farming methods that illuminates settlement patterns, family life, interregional trade, and other elements of tribal life.