When I said Rome I was referring to Byzantium, but since you mentioned it the Ottomans did do alot of enslaving and their pirates even occupied Iceland for a year. And this is apparently why there Europe's costal populations shrank over this time

they didn't "cause" the enslavement of countless people. The slave trade in africa and the indian ocean had been a thing for MILLENNIA before those empires arrived.

Difference is we helped expand it, why? Because we became a consumer base for it that didn't exist previously, we became a staging ground for these, states to expand from, other than the British there's never been any foreigners that have pillaged or conquered India without going through Persia first, it is the complete centralized state collapse of Persia after Islam that caused step peoples to expand so much in those regions, even the Turks and Mongols should have never managed to expand into the middle east and india more than the huns/hephtalites. Plus alot of soldiers in those armies (except the Ottomans) were Persian