Tlahtoāni is a historical title used by the dynastic rulers of āltepēmeh, autonomous political entities formed by many pre-Columbian Nahuatl-speaking peoples in the Valley of Mexico during the Postclassic Period. The title of huēyi tlahtoāni was used by the rulers of the Aztec Empire, an alliance between the āltepēmeh of Tenochtitlan, Tetzcoco, and Tlacopan.