The Aztec empire was important for a number of reasons. First, it was one of the largest empires in the world at the time, spanning much of Mesoamerica. Second, the Aztecs were a highly advanced civilization, with a rich culture and sophisticated architecture. Third, the Aztecs were a powerful military force, and conquered many neighboring peoples. Finally, the Aztecs had a complex political and economic system, and controlled a large amount of trade.