What was the legendary rich kingdom north of Mexico?

The legendary rich kingdom north of Mexico is Aztlan. Aztlan is the mythical place of origin for the Nahua peoples of central Mexico, such as the Aztecs. It is believed to have been located somewhere in northwestern Mexico or the southwestern United States. The Aztecs believed that Aztlan was a beautiful and fertile land, and that their ancestors had left it to found the city of Tenochtitlan.