The Middle Passage describes the Alantic slave trade that brought people from Africa to North and South America and to the Caribbean.
In the Middle Passage they traded people (slaves) in exchange for products and merchandise. North and South America got sugar, cotton, tobacco and coffee to Europe. From Europe they would take those goods and trade them for guns, iron, cotton cloths, and rum. Then they would trade them in for slaves in Africa. The Middle Passage is the way back to South and North America with slaves.
This is why it was called Triangular Trade.
It formed a Triangle because boats went and left Europe went to Africa and then to America to return back to Europe.
In the slave quarters, and even later, I heard whispered conversations among the coloured people of the tortures which the slaves, including, no doubt, my ancestors on my mother's side, suffered in the middle passage of the slave ship while being conveyed from Africa to America. Up From Slavery by Washington, Booker T.