What are you arguing? That side genocided in the past so other side please go ahead and do so now? Do you realize how absurdly callous that sounds? This isn't a board game we're playing with wooden figures for pieces. These are human lives. We have a chance to do something about these people who are suffering today, now.
Yes. I am not here to impress you with my morality. I'm just saying that it's awfully convenient for the side who did so in the past and reaped all its advantages without meaningful reparation to suddenly care about some strangers in some faraway land now.
And this is without going into what the Western powers directly did to China back in the day.
I care about these people. I don't have a time machine to go back and save the Native Americans or Greenlandic Inuits or Jews from the predations of world powers. It's not awfully convenient for me to care about the genocide of a million people. If I was alive during World War 2 and I received multiple, independent reports that a genocide was being committed by a foreign power, I would be agitating for that foreign power to be held accountable just as I am today.
I dearly hope we've moved past barbaric eye for an eye justice.