The 18th century was profoundly marked by the slave trade. Slavery was present in civilizations on all continents throughout post-hunter-gatherer history. The importation of slaves from the Old World started on continental North America in August 1619 as a form of indentured servitude, and continued in the next centuries. Slavery also occurred in Africa previous to Europeans capitalizing on selling slaves. Africans were sometimes hired to collect others off the coast, and bring them back to European ships. Because of this trade, the dependent states remained dependent as their populations were suffering from the slave trade.