How did the ruler establish legitimacy in the aztecas

Aztec is the name popularly used today to label the people who dominated central Mexico around 1500 CE. Actually, "the Aztecs" never used the term to describe themselves; rather, they were Nahuatl-speaking peoples divided into about twenty different ethnic groups. The most famous of these groups, and the preeminent one when the Spaniards arrived in Mexico, were the Mexica.

The Mexica arrived in the basin of Mexico (where Mexico City stands today) probably some time during the thirteenth century CE. According to their own legends, they arrived along the western shores of Lake Texcoco as an impoverished, uncouth group into a region that was already fairly fully occupied by a series of kingdoms. Despised as barbarians by the existing inhabitants, their only skill was an aptitude for warfare under the strong influence of their patron god of war, Huitzilopochtli.

Gradually, the Mexica grew stronger. They settled their capital, Tenochtitlan, sometime around 1325, and toward the end of the fourteenth century began to make a concerted drive to achieve a position of strength in the region. In 1428, they and several allies overthrew the Tepanecs of Azcapotzalco, the most powerful kingdom in the basin of Mexico at the time. In one sudden move, the Mexica had become the most-powerful group in ancient Mexico