Answer:
They made them pay "tribute" or a form of tax
Step-by-step explanation:
After conquering a certain region, Aztec empire offered the people who live there in a proposal. They will be granted the protection of Aztec's military from that point onward. But in return, they had to pay tribute for the Aztec empire.
The tributes mostly taken from some percentage of production that the people had within a certain time period. (most of the tributes are in the forms of agricultural products, animal products and precious metal.)