Excerpts from Books and Wikipedia
"The chief ordered the construction of a city (named Tenochtitlan after him), the site of which now lies buried beneath Mexico City." [Furtado: 1001 Days] "The Mexica found the city of Tenochtitlan. This would later be the epicenter and capital of the Aztec Empire until the Siege of Tenochtitlan 200 years later." [Wikipedia: Timeline of Middle Ages] "After about 1200 CE, various nomadic peoples entered the Valley of Mexico, including the Mexica. When they arrived, they 'encountered the remnants of the Toltec empire (Hicks 2008; Weaver 1972).' There were other groups, but all are believed to have the same origin in Aztlan." [Wikipedia] "Aztlán (...) is the ancestral home of the Aztec peoples. . . . Historians have speculated about the possible location of Aztlan and tend to place it either in northwestern Mexico or the southwest US, although there are doubts about whether the place is purely mythical or represents a historical reality." [Wikipedia]