BEFORE AN AUDIENCE of 500 people on the outskirts of Pamplona, Maialen Lujanbio, the reigning champion of bertsolaritza, the Basque oral tradition of improvised song, steps up to the microphone. She stands in silence, thinking.

Ms Lujanbio is composing a bertso, the rules of which are simple but exacting. Given a theme or a prompt, bertsolaris invent a poem of between eight and 12 lines, which must fit a prescribed rhyming form. Next they choose a melody from thousands of traditional tunes, or coin a new one on the spot. Bertsolaris usually think for around 30 seconds. The silence can feel chasmic. And then they sing.

Pamplona is in Navarra, on the edge of the Basque country, but some of its population speaks Euskara, the Basque language; the festival was one of 2,000 such events a year across Basque-influenced regions in Spain and France, according to Estibalitz Esteibar of Bertsozale Elkartea, an association that promotes the tradition. They range from bertso dinners, in which a feast is capped by an impromptu performance, to the Basque country championship, a rap battle that is the climax of a quadrennial contest. In 2017, 15,000 tickets were sold for the championship; almost half of all Basque-speakers tuned in on television.

No other oral folk art commands this kind of audience. But the success of bertsolaritza was not spontaneous: it was planned. Various strands began to coalesce into something resembling today’s version in the 1930s, shortly before the Spanish civil war broke out. Under General Franco, the tradition was repressed, as was Euskara itself; in-migration from other parts of Spain diluted use of the language further. The championship was firmly re-established only in 1980. Bertsozale Elkartea was founded “to stop the tradition dying,” says Igor Elortza, a bertsolari.

The revivals of bertsolaritza and Euskara have gone hand in hand, said Ms Esteibar. Volunteers set up a network of bertsolaritza schools. Meanwhile, encouraged by the regional government—dominated by Basque nationalists—public schools began to teach in Euskara; wizened bertsolaris gave lessons. Almost everyone at the Pamplona shindig said they were exposed to the tradition at school, rather than at home. Euskara’s recovery has been boosted by the fact that it is required for most jobs in the regional administration. A study in 2016 showed that 34% of people in the Basque country speak it (up from a quarter in 1991); that includes 70% of Basques under 25.

This has pumped fresh life into bertsolaritza. Not long ago, it was “something for men, in the bar, at night,” said Ms Esteibar. Increasingly, the typical bertsolari is young, urban and educated. They often deal with contemporary issues of family, society, ethnicity and politics; in Pamplona the songs touched on Venezuela, the closure of squats and the gender politics of dinner parties. The growing role of women is one way bertsolaritza is evolving. Ms Lujanbio is the first female champion in a historically male discipline (see picture).

Enthusiasts in Pamplona described bertsolaritza as a social movement. The poetry is central, but it is the link to Basque language and identity that ensures the appeal. In politics, Basque nationalism has dark, exclusionary undertones, yet the sense of community at these gatherings is wholesome and enchanting. Over bitter cider and sweet shots of Patxaran, a sloe and anise liqueur, everyone had their own story about how they got hooked—but hooked was the word they used. It is the camaraderie that draws the bertsolaris to the continuous events, few of which pay. “It’s why I’m here,” said Xabi Igoa, a young practitioner.

The history of bertsolaritza explains the atmosphere in the auditorium. The silence before the bertsolari begins to sing is reverential. The audience is expectant but generous: they laugh and whoop when the performers please them, and will them to recover when they stumble. From time to time, the pattern of rhythm and rhyme in a bertso reveals what the last few lines will be before the poet delivers them. These moments, when the audience and the bertsolari sing together, feel almost religious.