Final answer:
The Aztecs had firm control over the majority of the city-states in central Mexico by the time the Spanish conquistadors arrived.
Step-by-step explanation:
The Aztecs, who built the city of Tenochtitlán, controlled an extensive empire in central Mexico by the time the Spanish conquistadors arrived. The Aztec federation, which rose to dominance in the 14th century, subjugated other city-states and required taxes and tributes from them.
Though there were some groups that resented Aztec rule, such as the Tlaxcalan, who allied with the Spanish, the Aztecs had firm control over the majority of the city-states in central Mexico.