It was used by the Spanish crown for slavery. The goal was to use Native Americans as a slave labor source. The encomienda system was a method by which the Spanish crown rewarded colonial settlers by entrusting them with a group of natives whom they would civilize and convert to Christianity, in return for gifts in the form of labor, taxes, or goods.
It didn't work because the Native Americans knew the land and could escape easily. they also were not immune to the diseases and died.
