 In the 1960s and early 1970s, researchers identified numerous sites in South Carolina and the Southeast that they associated with what they have classified as South Appalachian Mississippian culture.The settlements developed about 1000 CE, later than did some of the largest settlements to the northwest that were closer to the Mississippi River and its tributaries.Town Creek Indian Mound, a National Historic Landmark located across the border in present-day Montgomery County, North Carolina, is a surviving platform mound and archeological village site of this Pee Dee culture.