Barbary Slavegirl — Allan Aldiss

This story takes place at a time when European girls really were captured by the Barbary Corsairs and sold in the slave markets of North Africa.

Such women really were totally at the mercy of the rich men who owned them, and of the black eunuchs who supervised them. The Barbary States did have a reputation for treating Christian slaves unbelievably harshly, almost as animals, and there actually were slave breeding farms in the Ottoman Empire ... and although you won't find Marsa on the map, it could well have been there.