sentences:  The dramatic change may be the result of the Tequila Valleys region receiving an influx of migrants from elsewhere, likely the Bajío region of Guanajuato.Contrary to common beliefs, this does not represent a “Toltec Invasion,” but the establishment of new communities from outside of the Tequila Valleys.The Postclassic period dates from 900 to 1400 CE This period marks a return in population levels at the site to its estimated Classic period levels.