The Middle Passage was a triangular trade route between Africa, the New World, and Europe. This passage began in Europe, where ships were loaded with goods and sent to Africa, where they also traded African slaves.
African slaves were then traded for raw materials, which were returned to Europe to complete the "Triangular Trade". The Middle Passage was the stage of the triangular trade in which millions of Africans were shipped to the New World as part of the Atlantic slave trade.
