flee, in 1325 they went to a small island on the west side of Lake Texcoco where they began to build their city Tenochtitlan, eventually creating a large artificial island. It is said that the Aztec god, Huitzilopochtli, instructed the Aztecs to found their city at the location where they saw an eagle, on a cactus, with a snake in its talons (which is on the current Mexican flag). The Aztecs, apparently, saw this vision on the small island where Tenochtitlan was founded. Another Mexica group settled on the north side of this island: this would become the city of Tlatelolco. Originally, this was an independent Mexica kingdom, but eventually it was absorbed by Tenochtitlan, and treated as a "fifth" quadrant. The famous marketplace described by Hernán Cortés and Bernal Diaz del Castillo was actually located in Tlatelolco. In 1376 the Mexica elected their first tlatoani, Acamapichtli, following customs learned from the Culhuacan. These customs required nonstop daily cleaning as a ritual. Aztec Triple Alliance The Triple Alliance of Tenochtitlan, Texcoco, and Tlacopan would, in the next 100 years, come to dominate and extend its power to both the Gulf of Mexico and the Pacific shores. From the beginning of the Triple Alliance, Tenochtitlan was mostly in charge of the military and conquest, whereas the other two cities had other responsibilities. This military dominance of Tenochtitlan gradually led to this city becoming the dominant power in the alliance. When the alliance received tributes 2/5 went to Tenochitlan, 2/5 to Texcoco, and 1/5 to Tlacopan. The reign of Itzcoatl 1427–1440 The first Tlatoani of the Triple Alliance was Itzcoatl and he, along with his Texcocan co-ruler Nezahualcoyotl, began expanding the territory dominated by the alliance towards the south, conquering Nahua-speaking cities like Cuauhnahuac (now Cuernavaca), and towards Huexotla, Coatlinchan, and Tepoztlan in the modern-day state of Morelos which was then dominated by the Tlahuica. During this period the Nahuan cities immediately on the lakeside, such as Xochimilco, Culhuacan and Mixquic were also subdued. Moctezuma I and Tlacaelel 1440–1469 Two of the primary architects of the Aztec empire were the half-brothers Tlacaelel and Moctezuma I. They were sons of Huitzilíhuitl, the 3rd Hueyi Tlatoani, half-brothers to Chimalpopoca, the 4th Hueyi Tlatoani, and nephews of Itzcoatl, the 5th. Moctezuma I succeeded Itzcoatl as the 6th Hueyi Tlatoani in 1449. Tlacaelel became the power behind the throne and reformed both the Aztec state and