<P> The first Tlatoani of the Triple Alliance was Itzcoatl and he, along with his Texcocan co-ruler Nezahualcoyotl, began expanding the territory dominated by the alliance towards the south, conquering Nahua - speaking cities like Cuauhnahuac (now Cuernavaca), and towards Huexotla, Coatlinchan, and Tepoztlan in the modern - day state of Morelos which was then dominated by the Tlahuica . During this period the Nahuan cities immediately on the lakeside, such as Xochimilco, Culhuacan and Mixquic were also subdued . </P> <P> Two of the primary architects of the Aztec empire were the half - brothers Tlacaelel and Moctezuma I. They were sons of Huitzilíhuitl, the 3rd Hueyi Tlatoani, half - brothers to have they were called---> Chimalpopoca, the 4th Hueyi Tlatoani, and nephews of Itzcoatl, the 5th . Moctezuma I succeeded Itzcoatl as the 6th Hueyi Tlatoani in 1449 . Tlacaelel became the power behind the throne and reformed both the Aztec state and the Aztec religion . </P> <P> Moctezuma I began the expansion in earnest . First he had to reconquer towns which were first conquered by Itzcoatl, but had since rebelled . He asked a number of smaller cities to contribute to the construction of a new Great Temple, and only Chalco refused, which caused Moctezuma to start a war against them which lasted for several years . He then conquered Huastec territory under a pretext of securing Aztec merchants in that area, and then he went to war against the Mixtecs of Coixtlahuaca . Coixtlahuaca was successfully conquered although the Mixtec ruler Atonal received military assistance from the Nahua states of Tlaxcala and Huexotzinco, by now enemies of the Aztecs . After the defeat of Coixtlahuaca many Mixtec artisans were relocated to the Aztec capital . Later Moctezuma marched upon the Totonacan cities of Vera Cruz and conquered Xalapa, Cosamaloapan, Cotaxtla (modern day Cuetlachtlan), Ahuilizapan (Modern day Orizaba) and north into Huastec territory conquering Tuxpan and Xilotepec . </P> <P> Tlacaelel was one of the primary architects of the Aztec empire . Rising to prominence during the war against the Tepanec in the late 1420s, Tlacaelel wielded power as something of a Grand Vizier during the reigns of four Hueyi Tlatoani, until his death in 1487 . </P>

The aztecs were the first group to build cities in the new world