Among many migrant groups that began to arrive in the Valley of Mexico in the 13th century, four were destined to play a critical role in the rise of the Aztec empire.

The first major group were the Chichimecs, said to have been led by the chieftain Xolotl. The second group were the Tepanecs, who probably trace their origins to the Valley of Toluca and the Matlazinca abd Mazahua ethnic stock of that region. The Tapanecs intermarried with the existing peoples of the Valley of the Mexico and eventually settled at Atzcapotzalco on the western side of the basin. The Acalhua were the third mogrant contingent, who moved into the eastern side of the basin in what was then unoccupied land.

By the time that the fourth group arrived toward the middle of the 13th century, few lands remained unclaimed. This group was a mixture of various others, also intermarried before settling on the islands that became Tenochtitlan and proclaiming themselves the Mexica. The involvement of this people set the stage for the dynamic changes in the 15th century. Of all the migrant groups, the early history of the Mexica is the most well known. The legends of their origins, travels, and adventures, and their various settlements and battles before founding Tenochitilan are recounted in the schoolbooks of Mexico today.

The story of the Aztec migration and settlement is one that can rarely be proved or explained historically. The following outline will be one taken from the book written by Richard F. Townsend. The book Aztecs is one that attempts to present the history, rise, and fall of the Aztecs. It is the book that I primarily used for this page. Well on to the rise of the great Aztecs.