Most likely Brazil.
Ah, I thought we were speaking of the USA. You do though make a point. Always best to keep a cool head. Should one want to get techincal, more slaves were taken from east Africa by Moslems over the centuries than west Africans taken to the new world. I believe Livingston, Burton and Stanley address this issue. Not that this has a tie in with the Civil War. Unless should one take into account Stanley's military service.