Lots of people question the unified nature of Europe! Whole world wars have been fought over that very question. Regardless of cultural or racial similarities, whether there's a single government or not is a major factor in deciding if an area is a unified entity. That's not some British invention, it's fundamental to the whole concept of a nation state to begin with.

Please stop posting flamewar comments to HN, including religious and nationalistic comments. You've been doing it repeatedly, unfortunately, and we ban that sort of account.

https://news.ycombinator.com/newsguidelines.html

All the people who died in the Thirty Years' War would like to have a word with you.

To be fair, that came quite a bit after the medieval period. However, there's plenty of division during the Medieval period.

Eg the Iberian peninsula wasn't even Christian during most of that time. And neither was much of Eastern and Northern Europe.