The first major culture to inhabit this area was the Tlahuica, whose main settlement was where the city of Cuernavaca is today. The Tlahuicas have inhabited this area at least since the twelfth century.
The first incursions south into the area by peoples of the Valley of Mexico occurred in the twelfth century, when a lord named Xolotl (ruler of Tetzcoco) conquered most of the Valley of Mexico. An allied Chichimeca tribe also moved south into what is now northern Morelos state, making Techintecuitla lord of the Cuernavaca area, with the Tlahuicas concentrated in the nearby towns of Yecapixtla and Yautecatle. According to the Tlatelolco Annals, in 1365, the lord of Cuernavaca, Macuilxochitl, tried to conquer lands as far as the Valley of Mexico, but was met by the lord of Chalco, Tzalcualtitlan, with similar ambitions.
The first Aztec emperor, Acamapichtli, began to expand his empire to the south of the Valley of Mexico and beyond in the 1370s. His successor, Huitzilihuitl, was eager to press on into what is now Morelos state because of the cotton grown there, it was called Tlalnahuatl at that time. He asked to marry the daughter of the ruler of Tlalnahuatl, but was rejected. That rejection started a war that ended with an Aztec victory in 1396. Huitziliuitl then married the princess and Moctezuma I was born of the union. Credit for the conquest of Cuernavaca is given to Acamapichtli in the Mendocino Codex, but later writings cite Itzcóatl, or even Moctezuma I, as conqueror. The conquered dominion, Tlalnahuac, was roughly the size of the modern state of Morelos, and subsequently was renamed as Cuauhnahuc by the Aztecs.
From 1403 to 1426, this province grew in strength, subduing neighboring peoples such as the Coauixcas. Eventually, the province, then ruled by Miquiuix, rebelled against the Aztec Empire. This rebellion was put down by Totoquihuatzin and Netzahualcoyotl in 1433. This area then joined in the conquests of what now are known as
