If I remember correctly they also had massive slave markets or at least massive slave exports.I thought spices were what fueled the East African slave trade. Didn't Zanzibar have a massive clove plantation?
Or maybe technically speaking not so massive exports, since the horror stories of the East African slave trade includes
virtual reefs made out the would-have-been eunuchs who didn't survive the process (9 out of 10 according to wikipedia).
Come to think of it, a strong Chinese influence on how to produce eunuchs (slower and safer, from what I understand;
at least, the method I recall a description of - for court eunuchs, one presumes - included more steps and equipment than
a large pair of scissors), might have some kind of effect. Not sure what, though.