Teopantecuanitlan is an archaeological site in the Mexican state of Guerrero that represents an unexpectedly early development of complex society for the region. The site dates to the Early to Middle Formative Periods, with the archaeological evidence indicating that some kind of connection existed between Teopantecuanitlan and the Olmec heartland of the Gulf Coast. Prior to the discovery of Teopantecuanitlan in the early 1980s, little was known about the region's sociocultural development and organization during the Formative period.