During the twelfth or thirteenth centuries the third had greatest of the Mexican civilizations arose – the Aztecs. They were a warlike race which gradually grew in power, becoming the strongest nation in Mexico. Their capital, Tenochtitlan, was built on islands in a marshy area where Mexico City stands today. They worshiped a blood-thirsty pantheon of gods, led by Huitzilopochtli, the sun god. These gods had to be pacified by the sacrifices of hearts torn from the living bodies of human victims. The Aztecs had reached the height of their power when, in 1519, they were invaded by a Spanish army of five hundred men led by an adventurer, Hernan Cortez. Although the Aztec king, Montezuma, could call upon an army of thousands of warriors, he was convinced that Cortez was a god called Quetzalcoatl returning in human form to avenge himself, and so he did virtually nothing to save his people. The Spaniards easily conquered the Aztecs and within a few years the Aztec civilization had been completely destroyed.