The Aztec Empire rose to power in the 14th century, originating from Aztlan and settling in the Valley of Mexico. They formed a triple alliance with Texcoco and Tlacopan, expanding through military conquests and alliances while developing a complex society and agricultural system. The empire's political structure centered around the Huey Tlatoani, supported by a hierarchical society and bureaucracy. Their military prowess, religious practices, and economic system based on agriculture, trade, and tribute allowed the Aztecs to dominate Mesoamerica until the Spanish conquest in the early 16th century.