"GPT4 will tell me Donbas is still Ukraine" But is it though? What's really the meaning of which country a region belongs to? Once somewhere has been occupied

"GPT4 will tell me Donbas is still Ukraine" But is it though? What's really the meaning of which country a region belongs to? Once somewhere has been occupied long enough, it usually becomes de-facto theirs. But how long is long enough? Other countries either do or don't recognize it and usually a consensus is reached, but not always.