It was here that the Great Aztec empire would be built (modern day Mexico City.)The Mexica, with their own land, were finally able to thrive and soon they had Tlatoani (King) who was recognized by other kings in the area as the spokesperson for the new Altepetl (city state.)

The fall of Teotihuacan in 750 CE created a power vacuum, and Nomadic peoples like the Chichimec began arriving in the region. The Mexica people are descendants of the Chichimec warriors, however their arrival into the valley was late, meaning that the political and social power of the Mexico Valley was already held and defended by other tribes and Altepetls (City States.) This left the Chichemec reliant on alliances with other Altepetls, and they were often forced to travels as alliances broke and enemies were made. They were also unable to establish their own society, and had to fit themselves into the social and political frameworks of other communities.

In one story, while in 'Tula' the Chichimec tragically broke a truce with the Nonohualca people after a man taken in by the Chichimec sacrificed 4 Nonohualco women. The Nonohualco blamed the Chichimec and made war on them, but both parties soon decided that it was the fault of the man who had killed the women. Too many had already died however, and the two peoples broke ties the same day, leaving Tula to become wanderers again.

Tenochtitlan, the Mexica capital, was built on an island in Lake Texcoco and connected to the mainland by three wide causeways with bridges that allowed canoe traffic and defense. At its center stood the sacred precinct with the Templo Mayor, palaces, temples, and schools. Surrounding this, the city was divided into four districts made up of calpulli, or neighborhoods, where commoners lived in adobe houses and nobles in larger stone homes. Canals ran throughout, making travel by canoe common. The great market at Tlatelolco (North side of the Island,) drew tens of thousands daily, trading food, tools, textiles, and luxury goods. The King's palace held gardens, aviaries, and a zoo with jaguars, monkeys, and exotic birds. Aqueducts brought fresh water from Chapultepec (Springs,) while floating gardens, supplied crops.