What was the Aztecs joined two other city-states to form a triple alliance?

The Aztecs joined with the city-states of Texcoco and Tlacopan to form the Triple Alliance in 1428. This powerful coalition enabled them to dominate the Valley of Mexico and expand their empire through military conquests and strategic alliances. The alliance significantly increased their resources and influence, leading to the establishment of the Aztec Empire, which became one of the most formidable civilizations in Mesoamerica.