Montezuma inherited an empire of five million people from his uncle, stretching from present-day Mexico to Nicaragua. At the time, the empire was made up of semi-independent city-states. One of the Aztec King's greatest achievements was to expand and centralize this empire. Within months of taking the throne in 1502, he changed from a man of good reason into a pitiless autocrat who declared himself a god. He wanted people to be afraid of him, as he believed that fear and ruthlessness were the only ways to stop the empire falling apart.