> I don't know why you're asking for an explanation of random unsourced and unqualified historical factoids (without mentioning e.g. which harems, which courts, where and in what time period, which seem kind of important specifics when using vague generalisations like "largely") - maybe ask whoever you learned that from unless you're "just asking questions".

I literally said Ottoman and Mamlukian harems. There was only one Ottoman dynasty in one place in one historical time period. As there was only one Mamlukian harem in one place in one contiguous historic period.

FYI both of those dynasties, as did many other kingdoms and empires, had a strong preference for Slavic and Caucasian (as in from the Caucasus) consorts, as can be seen from the ethnicities and religions of most of their dynastic rulers' mothers. And Islamic and Mongol rulers were notorious for keeping younger male slaves from both regions as companions. Heck, the Mamluk dynasty itself was formed by a bunch of Cuman and Circassian slaves who ended up being so powerful as to control their Ayyubid masters.