> have thousands of years of history with each other Not really. In many parts of what is now Germany, people spoke dialects that were incomprehensible even t

> have thousands of years of history with each other Not really. In many parts of what is now Germany, people spoke dialects that were incomprehensible even to people in the next valley; this was as recently as the 19thC. In the 20thC, a British leader could speak of Czeckoslovakia as "a faraway country of which we know little". Modern Frenchmen would regard their countrymen from 2K years ago as completely alien. Modern Greeks speak a language that is recognizably derived from ancient Greek, but in other cultural respects, modern and ancient Greeks are very different. Those ancient societies regarded their neighbours as barbarian enemies, not as neighbours they shared a culture with. It's only since (say) the 5thC AD that European culture began to become more homogenous. BTW, the idea that the US government is "unified" looks like a sick joke, from my perspective.