Remember that 100 years ago Lemburg belonged to the Austrian Empire. Then after WWI it became Lvov, part of Poland.
Then after WWII it became part of the USSR. Then after communism fell, it became Lviv, part of the independent Ukraine.
Populations in the area where shifted around each time.
And that’s only the last 100 years.. .
And that’s the area (Lviv Oblast) that my fraternal ancestors came from. If the border between Poland and Ukraine had been drawn further east then it would be part of Poland. Stalin and Khrushchev drew the boundaries to make much of eastern Poland part of the Soviet Union.
In that part of the world, in order to know what country you are in, you first need to know what century you are in.