Yes. History is so much easier when you decide when something started just to prove your point. Before there was only darkness 😱.
Discussion
I am from Lithuania that was maybe 20x size of it’s today territory (including parts of russia and ukrain) at some point in history. Am I entitled to reclaim that land ? Or maybe native Americans are entitled to claim the land from United States?
In a world where international law has no meaning anymore (if it ever had) you can reclaim whatever you want if you have the power to do so. If not, just try to have a good relationship with your neighbors so your country doesn't end up like Ukraine.