Behold the evils of Colonialism:
The photo above was taken in about 1907, and shows a British sailor sawing the shackle off the leg of an African slave.Where was that slave bound before he was freed by the British?
In 1907 there was no longer any market for slaves among white people anywhere in the world. In fact, there was probably no market at all for slaves except in black Africa or among the Arabs. In all likelihood that slave was going to be sold on the Arabian Peninsula or perhaps to African Muslims.
Who captured the slave?
He was probably captured by another black African from a neighboring tribe, either in warfare or as a part of a deliberate slave-taking raid. The Arabs rarely captured black slaves themselves, and this slave might have been brokered several times by African traders before arriving at his final owner.
In any case, both the slave-taker and the customer were almost certainly Muslims.