The Caddoan Mississippian area, a regional variant of the Mississippian culture, covered a large territory, including what is now eastern Oklahoma, western Arkansas, northeastern Texas, and northwestern Louisiana. Archaeological evidence has led to a scholarly consensus that the cultural continuity is unbroken from prehistory to the present, and that the Caddo and related Caddo language speakers in prehistoric times and at first European contact are the direct ancestors of the modern Caddo Nation of Oklahoma.  The climate in this area was drier than areas in the eastern woodlands, hindering maize production, and the lower population on the plains to the west may have meant fewer neighboring competing chiefdoms to contend with. Major sites such as Spiro and the Battle Mound Site are in the Arkansas River and Red River Valleys, the largest and most fertile of the waterways in the Caddoan region, where maize agriculture would have been the most productive. The sites generally lacked wooden palisade fortifications often found in the major Middle Mississippian towns. Living on the western edge of the Mississippian world, the Caddoans may have faced fewer military threats from their neighbors. Their societies may also have had a somewhat lower level of social stratification.  The Caddoan people were speakers of one of the many Caddoan languages. The Caddoan languages once had a broad geographic distribution, but many are now extinct. The modern languages in the Caddoan family include Caddo and Pawnee, now spoken mainly by elderly people.  Hernando de Soto led an expedition into the area in the early 1540s, he encountered several native groups now thought to have been Caddoan. Composed of many tribes, the Caddo were organized into three confederacies, the Hasinai, Kadohadacho, and Natchitoches, which were all linked by their similar languages.

Answer this question "What is Caddoan Mississippian?" by extracting the answer from the text above.
a regional variant of the Mississippian culture,