Quote Originally Posted by TheCurmudgeon View Post
My question is: was that a mistake? Should we consider the possibility of two peoples sharing the same territory but with differing political alliances?
Western Europe took a long time, centuries after the Treaty of Westphalia, to evolve systems of governance where peoples and politics coexisted with minimal violent conflict. Not to overlook what happened in Bosnia, Kosovo, the wider FRY and many other places, close to me Northern Ireland.

One of the largely forgotten episodes after 1918, partly as the League of Nations was responsible, were the number of population transfers, e.g. between Greece and Turkey in Thrace.

There were and remain a few places where sovereignty was shared, usually small tropical islands involving France and the UK.

Today it is difficult to see how partition and population transfer could happen by agreement.