Question: who joined the aztec civilization?
Answer: The Aztec Empire, or the Triple Alliance (Classical Nahuatl: Ēxcān Tlahtōlōyān, [ˈjéːʃkaːn̥ t͡ɬaʔtoːˈlóːjaːn̥]), was an alliance of three Nahua altepetl city-states: Mexico-Tenochtitlan, Texcoco, and Tlacopan.