From the 1620s, many of the Irish Roman Catholic merchant class in this period migrated voluntarily to the West Indies to avail of the business opportunities there occasioned by the trade in sugar, tobacco and cotton. They were followed by landless Irish indentured labourers, who were recruited to serve a landowner for a specified time before receiving freedom and land. The descendants of some Irish immigrants are known today in the West Indies as redlegs. Most descendants of these Irishmen moved off the islands as African slavery was implemented and blacks began to replace whites. Many Barbadian-born Irishmen helped establish the Carolina colony in the United States.