Since 1708, the majority of the population of the South Carolina colony were enslaved Africans, as importation of laborers from Africa had increased in recent decades with labor demand for the expansion of cotton and rice cultivation as commodity export crops. Historian Ira Berlin has called this the Plantation Generation, noting that South Carolina had become a "slave society," with slavery central to its economy. As planters had imported many slaves to satisfy the increased demand for labor, most slaves were native Africans. Many in South Carolina were from the Kingdom of Kongo, which had converted to Catholicism in the 15th century. Numerous slaves had first been held in the British West Indies, where they were considered to become 'seasoned' by working there under slavery, before being sold to South Carolina.