Two of the primary architects of the Aztec empire were the half-brothers Tlacaelel and Moctezuma I. Moctezuma I began the expansion in earnest. First he had to reconquer towns which were first conquered by Itzcoatl, but had since rebelled. He asked a number of smaller cities to contribute to the construction of a new Great Temple, and only Chalco refused, which caused Moctezuma to start a war against them which lasted for several years. He then conquered Huastec territory under a pretext of securing Aztec merchants in that area, and then he went to war against the Mixtecs of Coixtlahuaca. Later Moctezuma marched upon the Totonacan cities of Vera Cruz and conquered Xalapa, Cosamaloapan, Cotaxtla (modern day Cuetlachtlan), Ahuilizapan (Modern day Orizaba) and north into Huastec territory conquering Tuxpan and Xilotepec. Tlacaelel recast or strengthened the concept of the Aztecs as a chosen people and elevated the tribal god/hero Huitzilopochtli to the top of the pantheon of gods. In tandem with this, Tlacaelel increased the level and prevalence of human sacrifice, particularly during a period of natural disasters that started in 1446 (according to Durán). At the start of Tlacaelel's tenure, the Mexica were vassals. By the end, they had become the Aztecs, rulers of a socially stratified and expansionistic empire.