In the beginning, people speak different and act different for they live in distance. For instance in Europe nobles wouldn’t really bother teaching the peasants the same language they speak; and peasants wouldn’t really mind if the government post something that they could not understand on the city wall. After some successful political marriage it was pretty common in Medieval Europe that different regions (some don’t even share geographical borders) with different local languages and people share the same lord. Think about the Habsburg Dynasty. They had half Europe at the time. They even used different court languages to govern their vast dominion. It was the political norm for the feudal system in Europe, way before the emergence of modern nationalism. People were much more relaxed at the definition of border and nationality (though religion was a pretty serious matter for the identity). The definition of modern nationhood, one nation one people on language, came with the drastic French Revolution at the end of 18th century. As increasingly centralized polity imposed deliberate assimilation policy upon different local groups (i.e. like the spread of French in France or Belgium), local groups would also be awakened to resist the alien influence. In most cases the big power won. That’s why you got Germans are Germans, French are French, Italians are Italian nowadays. Occasionally locals managed to resist the imposition. That’s how those small nationalism movement emerged, such as the Flemish, the Baltic countries, the Basque, etc. After this what I call dramatic shuffling, the modern international political structure came to the stasis. People would move even for the sake of switching to different ethnic regime in between some artificial boundaries (like the Turk/Greek swap deal, or the expulsion of the Germans in Eastern Europe). In those wild days, borders change all the time, people come and go, some becomes prominent, some disappears, few stays the same. Nationhood and the border were not as sacred and eternal as we take for granted nowadays.
After years of struggle with the rise of modern nationalism, in today’s politics, most countries have one predominant majority of identity and language. A nation, defined by its geographical border is sacred and inviolable. This is the first thing that would cross over people’s mind when thinking of their country. What’s more, the few surviving local groups want to be out of their masters after the failed attempt of assimilation. Then big countries split into a number of small countries, like the case of Czechoslovakia, Yugoslavia, and even Georgia. As extreme as they appear, those peanuts size national movements are merely the extending tail of the whole modern nationalism movement starting 200 years ago.
But what’s the real trend now? As mentioned above, modern nationalism is coming to a dead end. Only small groups of laggards are still whining about the pie they didn’t taste, like Basque, Kosovo, or even Catalonia. The rest majority of people in the modern civilization are, on the contrary, a bit bored and tired of such modern tradition, especially after two biggest national wars. So people started to eye on the next step to find something to associate with… This is when things get out of control…
Out of control how? Out of control when people start to think that all humans should be treated equally and multiculturalism in a post-nationalism era is beautiful. So nationhood becomes less and less important now and borders are the symbols of old rigid outdated system. Intellectuals plan to break down the old ethnocentrism and build up something way larger to stimulate another rapid development just like nationalism did to us back then, as larger scale in polity brings larger potential of scientific advancement (people stay more focused). The first thing that needs to be gone is the nationhood and then the borders. But so far only the integration of European Union makes sense to me as the potential 1+1>2 game to reinvigorate Europe. The rest of those movements? There are simple too much discrepancy among the groups of people involved. Clustering the nationhood and borders only makes sense when the groups involved are somewhat in common at culture, IQ, economy etc. The whole ethnocentrism still remains strong despite being at the downward spiral, and we need to take that into consideration. The concept of nationhood would remain, but the entity of an independent polity would be upgraded. But then again, if it could not even be enforced effectively in Europe, then we certainly should forget about unconditional multiculturalism and think of other options to sustain our modern civilization.