Spanish conquest of the Aztec Empire
The Aztec government had started to use terror to keep control over the land it had taken over.  When the Spanish conquistadors got to Tenochtitlan, they said the Aztecs often held public ceremonies.  They would invite the leaders of the states they took over to come. Then they would do many human sacrifices. The conquistadors said that the Empire sacrificed 20,000 people every year  an average of 55 people a day.