By 1708, the majority of the colony's population were black Africans. They had been brought to Charlestown on the Middle Passage, first as indentured "servants" and then as slaves. In the early 1700s Charleston's largest slave trader Joseph Wragg pioneered the American large-scale slave trade. Of the estimated 400,000 Africans transported to North America for sale as slaves, 40% are thought to have landed at Sullivan's Island off Charlestown. Free people of color also migrated from the West Indies, descendants of white planters and black consorts, and unions among the working classes.