I am from Romania. It's interesting how historical boundaries reflect the Carpathians splitting our country in half.
As a person regularly crossing them, it does indeed feel they are different.
I think Muntenia is warmer socially (large family gatherings), but Transylvania is more economically developed (in fact, rent per square meter is highest in Cluj-Napoca, not the capital București).
For example, the borders after Israel's several wars.
Or anything to do with the world wars.
Also, lacks anything about the Russian empire's adventure into Alaska and down the coast almost to San Francisco.