One story has them originating from seven caves, which were excavated in 2000 in the state of Puebla, Mexico.  
Their name, meaning place of herons or place of whiteness, was adopted by one of their constituent tribes upon their 1325 arrival to their most famous location.  In 1428, their king Itzcoatl decided that people should not know about history and ordered all records destroyed, stymie-ing Fray Diego Duran's later efforts to determine their origins.  One story has them originating from seven caves, which were excavated in 2000 in the state of Puebla, Mexico.  For ten points, name this Mesoamerican civilization with capital at Tenochtitlan, whose king Montezuma was conquered by Hernan Cortes.
Their name, meaning place of herons or place of whiteness, was adopted by one of their constituent tribes upon their 1325 arrival to their most famous location.  
Aztecs 