Portugal was a pioneer in the trans-Atlantic slave trade, beginning its involvement in the mid-15th century. Portuguese explorers and traders were the first to establish a direct sea route to Africa, initiating the capture and transportation of African slaves to European and American territories. Between the 15th and 19th centuries, Portugal transported an estimated 4.5 million Africans, primarily from modern-day Angola, Mozambique, and Guinea-Bissau. The slaves were mainly taken to Brazil, which was Portugal’s largest colony, as well as to Portuguese colonies in the Caribbean and other parts of South America. The Portuguese used slaves primarily for labor on sugar plantations, which were the backbone of their colonial economy. Portugal officially abolished slavery in 1869, though the trade had significantly declined earlier in the century due to international pressure and economic changes.