 Complete the following phrase:  Following an earlier expedition to Yucatán led by Juan de Grijalva in 1518, Spanish conquistador Hernán Cortés led an expedition entrada to Mexico. Two years later, in 1519, Cortés and his retinue set sail for Mexico. Cortés made alliances with tributary city-states altepetl of the Aztec Empire as well as their political rivals, particularly the Tlaxcaltecs and Tetzcocans, a former partner in the Aztec Triple Alliance. Other city-states also joined, including Cempoala and Huejotzingo and polities bordering Lake Texcoco, the inland lake system of the Valley of Mexico. The 