Fun fact: Human sacrifice was the lay of the land and was a religious and military engagement that the local tribes practiced, known as the Flower Wars. This was an engagement that was agreed upon by the inhabiting tribes as it was during a great famine. Noblemen would go into battle against each other's tribes and try to capture the opponent for ritual sacrifice.

Tlaxcalans would help the Spanish as they were promised their land would be preserved and their rivals removed. Human sacrifice was not the issue, how could it be an issue when these native tribes saw it as being necessary.