Approximately 1000 to 1200 CE local Weeden Island peoples began adapting and adopting intensive maize agriculture, the building of platform mounds for ceremonial, political and religious purposes and making a new variety of ceramics, changes likely influenced by contact with the major Mississippian culture centers to the north and west. Early archaeologists thought that the Fort Walton culture represented the intrusion of peoples from Mexico or Mississippian cultures from the northwest replacing the indigenous Weeden Island peoples, but by the late 1970s this theory was generally discounted.