The Otomis were the first to settle this area, although the date of their arrival is in dispute. Over time, this migration came in waves, mixed with Nahua migrations which began after the fall of Teotihuacan in the last Classic period. The population became mixed in the state but eventually the Nahuas became dominant. By the 14th century, the last waves of Otomi migration came to the area, fleeing the rising Aztec Empire in the Valleys of Mexico and Toluca. The Otomis managed to remain relatively dominant in the Ixtenco /Huamantla area, but as vassals of the Tlaxcallan dominion, receiving land in exchange for military service. These same Otomi people were some of the first to fight Hernán Cortés’ initial incursion into central Mexico, and after defeat, allied with the Spanish to conquer the Aztecs .