Contact with industrialized nations brought Muslim populations to new areas through economic migration. Many Muslims migrated as indentured servants, from mostly India and Indonesia, to the Caribbean, forming the largest Muslim populations by percentage in the Americas.[288] The resulting urbanization and increase in trade in sub-Saharan Africa brought Muslims to settle in new areas and spread their faith, likely doubling its Muslim population between 1869 and 1914.[289] Muslim immigrants began arriving, many as guest workers and largely from former colonies, in several Western European nations since the 1960s.