Which Aztec emperor expanded the empire to its greatest size?

Ahuitzotl expanded the Aztec Empire to its greatest size. He ruled as the eighth tlatoani of Tenochtitlan from 1486 until 1502 and is widely regarded as one of the most successful military leaders in pre-Columbian Mesoamerica.

After taking power, Ahuitzotl quickly suppressed a rebellion in the Huasteca region and launched campaigns that greatly enlarged Mexica territory. His conquests extended Aztec influence toward the Pacific coast, the Mixtec and Zapotec regions, and areas reaching into what is now Guatemala. He also strengthened tribute networks and consolidated control over existing subject states.

A common mix-up is to choose Moctezuma II because he was the ruler encountered by Hernán Cortés. Moctezuma II governed at the empire’s famous final stage, but the empire’s maximum territorial expansion is generally credited to Ahuitzotl. His successor, Moctezuma II, inherited an already vast imperial system.