In the correlation of peoples and countries to talk about 'shame' is contraproductive in any way.
Within civilizations based on certain moral rules shame is a self induced punishment for to prevent humans to violate those rules by urging them to make themselves feel bad. The idea of shame is to either avoid it in the first place, or to get rid of it by somebody's forgiveness.
Shame is innapropriate for a people or a country. Peoples or countries cannot neither feel shame, nor can they forgive each other. Only individuals can.
It is not about to feel ashamed of what the ancestors did. We are not responsible for what they did. Without influence there is no responsibility. Nobody can be hold accountable for what others did, and which she or he had no influence on. Everybody is responsible for their own actions, not for other's. And we didn't do what happened eighty, ninety, hundred, or several hundreds of years ago.
Such ideas may even lead to vendetta, a most immature way to avoid dealing with things in underdeveloped societies. Nothing good for nobody ever came from this. It produces only even more bad, and worse things. So you better don't even remotely start anything like that in the first place - doesn't matter who was 'wrong' or 'right'. All ways are better to deal with things instead of worsen them.
If your people in history did something terrible - and many countries/peoples in history in one or the other way did; which is also an immature, childish, undecieved, and contraproductive way believing one could deal with it by pointing at others and say:'they also did something bad.' This neither changes, nor improves anything - you were educated to see it. You understand it was wrong, and bad. So there is the awareness of the individual. From that comes the responsibility of a people or country. Which is neither to be mixed up with each other, especially not to be confused with shame. Nor does it mean the indiviual may get rid of the awareness because the people or country deals with the responsibility.
The responsibility to try the best to make up for the damages, and injustices done as far as it's even possible. But above all the responsibility to preserve the memory. Not only for your own people, but everybody not to forget. Which must also not be confused with putting others right. Also educate coming generations.
Responsibility to do everything needed such things will never happen again, ever.
This has nothing to do with shame.
No victim of injustice, and persecution benefits by the offenders are ashamed.
They simply want injustice, and persecution to stop, and never happen again. And sometimes redemption - which is not for the offenders to decide.
If you are going to tell individuals of a people or a country to be ashamed of what their ancestors did in history, then they want get rid of this bad feeling of shame. But they cannot. Because they cannot undo what cannot be undone, especially not what they never did. Nor can they change from the implied worse individual to become better ones, because they never were those bad individuals.
So, since it's impossilbe to get rid of a shame you cannot deal with since that's outside the system what shame is for, what people then do to get rid of this shame is to swallow and ignore it. And that's bad.
This not only brews subconsciously, producing weird, wrong, and bad attidudes. But above all the ignorance leads to the distruction of the memory. This means the terrible things happened in history are going to be underestimated, and forgotten, and so happen again.
So, please, don't talk about shame. Maybe about responsibility. Better about awareness.
Because it's not about to make people feel bad. Nobody profits from somebody else feels bad. This produces nothing useful for no one whatsoever.
It's about not to forget, to do everything such things must never happen again.