This study uses dozens of 16th- and 17th-century pictorial and alphabetic texts, written by both indigenous and Spanish authors, that trace the origins of various ethnic groups - including the Mexicas, Chalcas, Texcocans, Colhuas, and people of Cuauhtitlan - and relate the foundation of their altepetl in the Valley of Mexico. Navarrete shows how the migration of these groups into the Valley created a complex cultural and demographic mosaic, in which these groups exchanged ideas, beliefs, and symbols even as they competed with one another for resources and land. The work reconsiders distinctions between myth and history, showing that indigenous communities drew upon both to define their past and shape their identities in the context of dynamic change in the postclassic period. The richness of the source base and the careful reconstruction and analysis of these histories makes this work a significant contribution to the field of Mesoamerican ethnohistory.