Plus the fact that moslems would castrate the males they captured, cutting EVERYTHING off. That is why blacks never reproduced in Arabia.
The emasculated males then would be put to digging wells and other sort of killer jobs. If one died, another was cheap just across the mountains. There was an endless supply.
Muslims enslaved and exported, over the centuries, roughly the same number of black Africans as Europeans. They started much sooner and extended the trade a few decades longer. Their slaves went to Turkey, North Africa, Persia, India and such. They only stopped (mostly) because Europeans, mainly Brits, forced them to.
But they didn’t sell slaves directly to Europeans for shipment across the Atlantic. They probably would have, but the powerful black African kings along the coast wouldn’t let them.