W/r/t Russia: In the imperial period, Russia expanded east and occupied the lands of many small nationalities. The forced cultural assimilation of these nationalities occurred in the 20th century, and maybe before.
Since you appear to be interested and may have knowledge about this, perhaps you can offer an opinion about the reasons, from Russia’s perspective, for Russia’s invasion/extermination/genocide of Circassians (a nationality in the Caucasus, also known as Adyghe) in the mid-19th century.
Actually, Circassian tribes were once loyal to Russia but then succumbed to the dark side of islam, the worst kind: the kind that ottoman turks used to attack and plunder and destroy.
After years of horrible attacks and savagery commited by these tribes, the Circassian tribes were defanged.
We thank Russia for its service to humanity.
You need to study up on the savagery that the Russian people have endured over the years at the hands of invading Muslims.
As for the Russo-Caucasian war again read up on that.