I would like to point out, it was the constant practice of Human sacrifice in the Americas that a lot of tribes where more than willing to side with the Spanish to go "You want gold? Oh those dickheads that keep sacrificing people have a lot of that! Forget maps, I'll guide you to where those bastards live and help you kill them."

And also a justification for Spanish conquest.

The great thinker Francisco de Vitoria, for example, argued that conquest was unlawful and immoral, and that it could only be justified in cases where rulers imposed reprehensible customs like human sacrifice and cannibalism on their subjects. Some others had argued that the Americas were terra nullius and that they could be taken without legal justification.