Conflicting Colonial accounts of the Aztec conquest of Oztuma are resolved by correlating new archaeological data, a collection of Early Colonial documents from the town of Ixtepec, and other better-known sources. The correlation of archaeological and ethnohistoric data suggests that, contrary to some interpretations of the histories of the Aztec Empire, the Aztec fortress of Oztuma was separate from and contemporaneous with a Chontal fortified site known by the same toponym, and that the Chontal of Oztuma were not exterminated by the Aztecs during the rebellion of 1487. Instead, Chontal Oztuma maintained internal political cohesion while integrated into the Aztec hegemony. The Aztec and Chontal sites together formed the defensive line of the imperial frontier facing the Tarascans. This study represents a shift in focus in Aztec studies from the Aztec imperial core to its constituent hinterlands, emphasizing the complexity of political and strategic interactions.