What is different about the Aztec story for the founding of their empire and the story historians have constructed?

The Aztecs, who probably originated as a nomadic tribe in northern Mexico, arrived in Mesoamerica around the beginning of the 13th century. From their magnificent capital city, Tenochtitlan, the Aztecs emerged as the dominant force in central Mexico, developing an intricate social, political, religious and commercial organization that brought many of the region's city-states under their control by the 15th century. Invaders led by the Spanish conquistador Hernán Cortés overthrew the Aztec Empire by force and captured Tenochtitlan in 1521, bringing an end to Mesoamerica's last great native civilization.