The Aztecs believed that they would recieve "help" from their Gods if they sacrificed humans, usually their hearts.
For example, Aztecs would kidnap their enemies and force them to fight for their lives. Whoever lost, whether it was a member of the Aztec tribe, or the enemy, would be sacrificed. This sacrifice was followed by tremendous amount of corn growth, leading the Aztecs to believe that the Gods sent the corn because of the sacrifice.
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