Cahokia is a village in St. Clair County, Illinois, United States. The name is a reference to one of the clans of the historic Illini confederacy, who were encountered by early French explorers to the region. Early European settlers also named Cahokia Mounds after the Illini. This is an extensive prehistoric Mississippian culture urban complex located to the north in present-day Collinsville in Madison County. It is a UNESCO World Heritage Site and a State Historic Park.