Captive Africans followed many routes from their homelands to other parts of the world. The map shows the trans-Atlantic movement of these captives in comparative perspective for the centuries since 1500 only. Estimates of the ocean-borne trade are more robust than are those for the trans-Saharan, Red Sea and Persian Gulf routes, but it is thought that for the period from the end of the Roman Empire to 1900 about the same number of captives crossed the Atlantic as left Africa by all other routes combined.