In 1519, when Hernn Corts led his army into Tenochtitlán in the Valley of Mexico, that Aztec city was the capital of a far-flung tributary empire.

The emperor Motecuhzoma sat atop a complex social and political hierarchy, and the Aztec populace owed allegiance and tribute to nobles at several levels.

Below the emperor were the kings of subject city-states.

The Aztec dominion employed a policy of indirect rule, and imperial authorities supported local dynasties so long as they delivered their quarterly tribute payments on time.

Officials recorded these payments in documents such as the Codex Mendoza [see "The Codex Mendoza," by Patricia Rieff Anawalt and Frances F. Local nobles, who lived in both urban and rural areas, were subjects of their city-state king.

At the bottom of the hierarchy were the commoners, whose tribute payments supported all these nobles.

Aztec commoners must have had a heavy tribute obligation. First of all, there were millions of commoners, so the tribute burden was spread over a large population.