A CENTURY AFTER its collapse, Austria-Hungary lives on in the tidy Alpine town of Bolzano in northern Italy (Bozen to German-speakers). Viennese coffee houses and beer halls clatter and chatter with life. Streets have names like Bahnhofsallee. “Under Austria, life here was very plural. There were equal rights. People could speak what language they wanted,” notes Sven Knoll. Then, he adds, came Mussolini, who tried to Italianise the region by imposing language restrictions and encouraging migration from the south. Mr Knoll’s South Tyrol Freedom Party wants Austrian passports for German-speaking locals and eventually secession for the region, which was awarded to Italy after the first world war for its support of the Allies. The current right-wing government in Vienna is planning a new citizenship law, so the first goal is within reach. Mr Knoll hopes the second is only a matter of time.

Europe is a mixed and mingled continent, so maintaining borders that reflect where people feel they belong has never been easy. Today’s Catalonia (then Aragon) formed a union with Castile in 1479, but later became subordinate to it. In 1866 Prussia seized Schleswig from Denmark, putting many Danes on the German side of the line. In 1913 a dying Ottoman empire ceded majority-Muslim Kosovo to Serbia. The Trianon Treaty of 1920 gave Hungarian areas to Romania and created the new state of Czechoslovakia. Such deliberations were not always very thorough. In his diary entry for February 7th 1919 Harold Nicolson, a British diplomat at the Paris peace conference, wrote breezily: “Spend most of the day tracing Rumanian and Czech frontiers with the US delegation. There are only a few points at which we differ.”

The result of this slapdash border-design is that Europe’s map is speckled with “national minorities”—the minorities who did not migrate, but saw borders migrate over their heads. They include once-independent states incorporated into larger ones (like Catalonia or Scotland) but also groups who do not live in the country with whose dominant culture they most identify (like the Austrian-Italians of the South Tyrol). In recent decades it seemed European integration would be the answer. Conflicts between autonomists and centralisers seemed to be dissolving into a patchwork of mutually understanding European regions. Catalonia would remain in Spain, but would be autonomous and European. German-speakers from Bolzano could shop in Innsbruck using the common euro. Kosovars and Serbians would treat EU membership as a common goal.

As the passport debate in the South Tyrol shows, the route to settled, Europeanised relations between national minorities and the majorities with whom they rub shoulders is getting rocky once more. Old tensions never quite die. When a coalition of the centre-right People’s Party and hard-right Freedom Party ( FPö ) came to power in Austria last year, issuing passports for South Tyrolers was one of its aims—one particularly promoted by Heinz-Christian Strache, the FPö vice-chancellor. Barrelling into a beer cellar in Bolzano to the “Radetsky March” last month, he addressed a cheering crowd wearing dirndls and felt-collared Tyrolean jackets: “There is an Austrian minority here that we can’t forget! We want a Europe of national identities!”

The rise of populism across Europe has been accompanied by a surge in tensions between autonomists and centralisers. A new them-versus-us style of politics, the rise of social-media echo chambers and demagogues’ disregard for old political norms is inflaming them. Rightists in the poor eastern regions of Saxony in Germany increasingly rail against Sorbs, a Slavic group. A proposed land-swap between Serbia and Kosovo—trading Serbian-dominated parts of Kosovo’s north for the fertile Presevo valley in Serbia—could reignite Balkan conflicts. The recent referendum in Macedonia on a name-change to settle grievances with Greece failed partly because voters there noticed the populist swerve by Greek rightists, who are now stirring up anti-Macedonian sentiment in regions close to the border. Viktor Orban, the autocratic prime minister of Hungary, wants to give passports to ethnic Hungarians in Romania and Slovakia.

This trend is more than a reaction to economic woes. In fact it is most pronounced in Europe’s most successful regions. The South Tyrol is one of the wealthiest on the continent. Northern Italy, the richest part of the country, has long flirted with the idea of floating off to form a country called Padania. In booming Denmark, the right-populist Danish People’s Party has called for the annexation of Schleswig from Germany. A party representing the Russian minority in Latvia, which has become much richer since joining the EU , won the most votes in an election there last month. Catalonia is the most productive part of Spain, but has been fighting for independence from Spain to cut its payments to poor Andalusians.

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Autonomists in the South Tyrol reject the charge of populism, arguing that their goal is to be more European, not merely Austrian. Catalonian separatists portray themselves (though it is a stretch, given Spain’s modern democratic nature) as the freedom-seeking victims of a still-Francoist state. In Corsica separatists won a surprise 57% of the vote in an election in December, but their demand was reasonable rather than emotional: fair recognition within France. Scotland’s nationalism is if anything leftist, secessionists insisting that an independent Scottish state would be more, not less, welcoming to immigrant “new Scots”.

All of which should trouble Europe’s leaders. The continent’s integration was meant to solve such questions. But they are once more surfacing. A resurgence of old communal hatreds, even violence, in places like Northern Ireland or Kosovo is no longer as unthinkable as it was a few years ago. Populism sets people against people. And in a continent with as many peoples mixing and mingling as Europe, that is dangerous.