Mille Lacs Kathio State Park, also known as Kathio Site, is a Minnesota state park on Mille Lacs Lake. The park preserves habitation sites and mound groups, believed to date between 3000 BC and 1750 AD, that document Sioux Indian culture and Ojibwe-Sioux relationships. The park contains 19 identified archaeological sites, making it one of the most significant archaeological collections in Minnesota. The earliest site dates to the Archaic period and shows evidence of copper tool manufacture.