The ancestors of the Aztecs received a divine command to leave their homeland of Aztlan in 1116 AD and wandered for over 100 years before reaching Lake Texcoco. From modest beginnings in the swamps around the lake, the Aztec city-state of Tenochtitlan grew in size and power through alliances and warfare. After floods and famines in the mid-1400s, Montezuma I expanded the empire outside the valley. When the Spanish arrived in 1519, over 300,000 people lived in the great city of Tenochtitlan, which was larger and more prosperous than Seville.