And I'm not downplaying anything (and sure, the Russian Empire made justifications for what it did), I'm pointing out that my God - that was two centuries ago. By your measure, every modern American and Spaniard is a genocidal maniac...
Sure you are. You're bringing up excuses.
Antiquity ended at the dawn of medieval times. That's like half a millenium earlier than where you want to put it. 1863 is quite some distance into modernity, well into the age of the railroad.
I haven't made anything in this about individuals, rather centering it around Moscow, which has at times been sacked by mongols, crimean tatars and culturally dominated by Paris. But well yeah, the US is quite genocidal. So what? Do you consider it the golden standard of statecraft or something?
Moscow's reach for the Black Sea had nothing to do with anti-slavery idealism or whatever you're getting at, they wanted ports and trade and didn't consider muslims as human as christians. It also seems to me that you don't consider serfdom a form of slavery, only international slave trade, which isn't a position I share.