Racists from start to finish
South Carolina is a place made and improved on slave labor. Though many Indians in the area had converted to Catholicism, that didn't stop these fierce slavemongers from buying them off of victorious tribes and selling them off. This caused some Indian chiefs to fight and supply the most slaves for the most profit.
South Carolina was built largely by its proprietors, in the event that British hierarchies failed, the structure fell to a simple rich or poor lifestyle. Due to the long growing seasons and tropical climate of the area, slaves were a necessity. Indians, to meet this demand, have always attempted to trade fervently with Europeans, and so they began fighting to supply the most slaves of their own kind. Of course, African slaves were common as well, but the Indian slaves were nearby and readily available. Native american relations were never so tense as when they were destroying one another for slaves, but when the Yamasees were attacked and their trusted partners offered no support, they were furious and this rage was directed at the settlers. The war they started crippled indian trade, and caused South Carolina to eventually switch to African labor.