Answer
Moctezuma II, the ninth Aztec emperor, played a crucial role in the expansion of the Aztec Empire during his reign. He led numerous military campaigns and strategically formed alliances with other city-states, significantly extending the empire's reach and influence. Moctezuma II's expansionist policies resulted in the conquest of several neighboring regions, making the Aztec Empire one of the largest and most powerful civilizations in pre-Columbian Mesoamerica.