AFRICA embraces more than a thousand ethnic groups and languages lumped crudely together by colonial mapmakers. So it is surprising that bids for secession have become rare. The African Union (AU), like its predecessor, the Organisation of African Unity, frowns on the idea, since so many countries are artificial affairs where tribal loyalties often trump national ones. Separatist sentiment across the continent has also dwindled as governance has improved, federalism or decentralisation have been more widely accepted and democracy has become more entrenched. And past bids for secession still make Africans quail. The Nigerian civil war (1967-70), when the south-eastern region known as Biafra sought to break off, left up to 2m dead. A similar bid by Congo’s south-eastern province of Katanga in 1960 caused five years of mayhem.

In two other cases, long, bloody civil wars eventually led to internationally recognised separation. Eritrea’s secession from Ethiopia was accepted in 1993. And South Sudan was hailed as independent of the mainly Arab north in 2011 (though the new country has since fallen into internecine chaos). In both cases, peace accords were sealed by referendums.

When central government fails, separatist feeling on the fringe, often spurred by ethnic or sectarian strife, tends to rise. That happened two years ago in Mali, where the Tuareg people, together with assorted jihadists, sought secession or something like it. France and a regional alliance stepped in to prevent the split by force. In turbulent Libya there has been talk of Cyrenaica, its eastern part, bidding for autonomy or independence. And the Islamist fanatics of Boko Haram in north-eastern Nigeria seek to hold territory there as part of their would-be caliphate.

In other places where prosperity and stability have increased, separatist fervour has faded: for example, in oil-rich Angola’s little Cabinda enclave, Senegal’s Casamance regionand in a once-British coastal strip of mainly Francophone Cameroon. The two most serious unresolved cases for separation concern Western Sahara, claimed and controlled by Morocco, and Somaliland, which runs itself. The Saharans’ Polisario movement, egged on by Algeria, seeks independence for the phosphate-rich coastal strip from Morocco, which grabbed the strip after Spain left in 1975. Nearly half the AU, including South Africa, backs Polisario, but France and other big powers lean towards Morocco. An agreement to hold a referendum has foundered on the question of who would be eligible to vote in it. In global forums, Polisario’s cause may be fading.

In 2001 the Somalilanders, whose territory was separately administered (by Britain) before becoming part of Somalia in 1960, voted overwhelmingly in a referendum for independence from the rest of Somalia, which has been ravaged by two decades of civil war. The longer it can remain stable and relatively democratic, the better its chances of international recognition. Like other African separatists, its rulers look at the decision to hold a vote in Scotland and ask why they should not also be given an opportunity to depart in peace.