I used to work with a guy who was very insistent that he was Czechoslovak.
Not Czech nor Slovak but Czechoslovak !
Seemingly his Mother was one and his Father the other and he took great pride in his hybrid identity and allegiance to a country which no longer exists.
Probably loads of folk like that in the former Yugoslavia and USSR as well.
What about the United Kingdom of Great Britain and Ireland ?
Or the multiple Kingdoms which existed on both islands 1,000 + years ago ?
Historically just about the oldest recognisable country in Europe is France and even it’s borders have shifted on multiple occasions.