Why did Jesuits and Friars go to the Spanish colonies in the Americans?

A. They went to convert the native peoples to Catholicism.

They're groups of religious men whose duties is to go out into foreign land and spread their belief to that region. Some tribes responded really well to their teaching while some events ended up in confrontation. People tend to take in ideals they never heard of before but are centered in communities nearby to become one with the community.