Mainly three items were transported into Africa and traded in exchange for the captured Africans.
These three items were:
Guns
Liquor
Livestock
Two new routes were created as a result of this transportation.
The first route was the "Triangular trade" that was created as a result of the trade between Africa, Europe and the new world.
The second route was the "Atlantic slave trade" that was created for transporting Africans to the new world.