In 1375, villagers of the Franco-Spanish borderlands along the Pyrenees mountains settled their differences with a treaty and magnanimous feast. That pact is still celebrated today

Viewed from the Pyrenean foothills that rise up behind it, the Barétous valley in summer is a study in rustic tranquility. Beneath me in this little corner of southwestern France the landscape rolls lazily away, a light mist settling in its green patchwork hollows, wreathing plump old trees and far-flung clusters of slate and whitewash. Besides the distant bleats, moos and clunking of neck bells generated by his animals, there isn’t a manmade sound to be heard.

It’s a fitting backdrop for what can claim to be the world’s most durable peace treaty – an unbroken 638-year accord between the French Barétounais and the Basque Spaniards of the Roncal valley, just over the mountains. Yet the pact dates from an age when cross-border cooperation, or lack of it, was a matter of life and death. Death, mainly, in its grisliest, most medieval forms.

‘My life is all about grass and water,’ says Jean-Marc Salis, scratching his stubble in the well-worn threshold of the shepherd’s cottage that is his summer home, ‘and so was all that trouble back in the 14th century.’ We’ve left the misty foothills and climbed into a pin-sharp mountain morning up near the Pyrenean peaks of Arlas and Anie. Jean-Marc has been up on these tilted, boulder-strewn pastures since 5am, milking 250 sheep in the company of a trainee shepherd from Brittany. His family have been farmers in the Barétous for six generations, but Jean-Marc’s affinity goes back more than half a millennium.

Just across the green ridge above, a few cloven-hoofsteps inside Spain, his flock is browsing the verdant spring where, one summer dawn in 1373, a Roncal cowherd found a Barétounais counterpart from the wrong side of the border grazing his own animals. A frank exchange of views ended with the Frenchman lying dead on the mountainside, inciting a cycle of massacre and counter-massacre. In two years, 600 villagers from both sides were killed. ‘The old churches here are like fortresses,’ Jean-Marc says. ‘When the Spanish came down we locked ourselves inside.’

It would be pleasing to record that both sides took stock of the tragic futility and came to their senses, but the Barétounais were only obliged to seek a truce after a brutal defeat at the hands of their Basque neighbours, the Roncales. The victors proved magnanimous, drawing up a treaty in which the Barétounais would be granted seasonal grazing rights near their water spring in exchange for an appropriate annual tribute. At 11am on 13 July 1375, dignitaries and eminent farmers from both valleys met atop the 6,500ft Col de la Pierre St-Martin mountain pass, laid their hands together on the boundary stone and declared their peaceful intent. Then the Spanish delegation waded into cattle that the French had brought with them, and selected ‘three cows with good teeth, hide and horns’ for a feast. And so began what is variously known as ‘la junta’, ‘la traité’ and the Tribute of the Three Cows, an event that’s been held every 13 July since – except in 1944, when the Nazis suspected that the French were plotting to nip over the border en masse.

‘These days farming up here is more sheep than cattle,’ says Jean-Marc, though the paddock before him is noisily alive with an Old MacDonald mix: half a dozen excitable pigs being fattened for the family Christmas, scuttling hens and 40 stolid examples of the horned, bell-necked blonde d’Aquitaine cow that has been the ubiquitous local breed since well before that first tribute. ‘But we absolutely couldn’t survive without la traité. Our farms are small and we don’t have enough land to graze livestock all year. I bring my animals up here in July and that allows my pasture back in the valley to recover enough to make hay for the winter.’

When he’s not squeezing sheep’s milk into a bucket, Jean-Marc is heating, stirring and compressing it into dense, creamy-white roundels of brebis cheese. ‘I’ve been doing it since I was 10,’ he says, sipping black coffee from a battered enamel mug. ‘My son is 17 and he’s learning now. The Spanish make a lot too, but…’ His cheery wink reveals how the enmity of old has been sublimated into jocular banter about dairy products. In his father’s time, Roncal and Barétous shepherds met on the mountains to hunt bears and barter contraband; now, in dwindling numbers, they moan about bureaucratic interference (‘Every time a sheep farts I have to fill out a form,’ sighs Jean-Marc). There’s a knock at the sooty kitchen window: a rambler after a wedge of brebis. He does the trade, then watches his customer stride up the extravagant undulations. ‘People come here to relax, not to work,’ he says with a shrug. ‘There were dozens of shepherds when I was a boy, but now we’re close to single figures.’

The road back down to the Barétous descends through the highest treeline in Europe, and into what feels like an open-air greenhouse. Beech and oak coexist with tropical staples: it’s Berkshire with bananas. The haze seems to embalm the landscape and its easy pace of life, imparting an agelessness you rarely find around the bright, well-trodden Alps. It’s the same in the quiet towns along the valley, with their mighty ‘bring-out-your-dead’ front doors and rusty unlocked bicycles. This close to Spain I expect a little cross-cultural fertilisation, but the Pyrenees are a mighty barrier and, at its mid-eastern end, one sparsely bridged by roads that are closed for half the year and often treacherous.

In the Barétounais town of Arette, which exudes an air of undiluted Frenchness, there isn’t a foreign number plate to be seen. Sitting at his desk in the handsome and typically enormous town hall that dominates the tiny town square, mayor Pierre Casabonne cheerfully admits that most trans-Pyrenean excursions are dictated by prosaic economy: ‘We go there to buy cheap meat and alcohol, they come here for the cheap skiing. Our lift passes are half the price.’ Yet with his black hair and deepbrown eyes, Pierre has a distinctly Hispanic demeanour shared by most of his fellow Barétounais, and he’s dedicated to the treaty and the mutual heritage it represents. ‘When we all meet up there, it’s about a lot more than cows and farming. It’s friendship and history, it’s celebrating what makes us the same and what makes us different. The past inspires the present,’ he declaims, settling into that very Gallic mood of poetic philosophy. ‘And when I stand by the stone with my Spanish counterparts, I feel like a link in a very, very long chain.’

Pierre’s link is stronger than most. He’s close friends with the mayor of Isaba, the Roncal town just over the mountains, close enough to have been a witness at his recent wedding. He’s also doing his bit to close what he feels is a heritage authenticity gap. ‘The French mayors have always gone up in civil servant business suits, while the Spanish are in traditional Basque capes and collars. It looked bad and felt wrong.’ He proudly lays out a sepia photograph of the unsmiling 1898 French delegation, in berets and a heavy, formal variant of the donkey jacket. ‘My first act in office was to have these costumes made for us.’

The afternoon slowly unfolds in a bucolic haze, watching old men in berets prod muddy cattle through gates and young boys chase chickens around hot, whiffy barns. No-one I meet can call on fewer than four centuries of regional family heritage. ‘I’ve retired now,’ says a jolly, curiously youthful ex-farmer as we sip tiny bottles of shandy under his apple tree. ‘That’s my wife driving the tractor down there.’

Some surprising truths emerge. The French speak Spanish but not vice versa, and while the Barétous ranks among the poorest regions in France, the Roncal valley, in the north of industrialised Navarra, finds itself in Spain’s wealthiest province.

‘We’re the peasants,’ laughs the most conspicuous local I meet – a full-on musketeer sporting a velvet tabard and magnificent facial hair. Aramits, just up the valley from Arette, was home to an eponymous 17th-century seigneur upon whom Alexander Dumas based one of his trio. ‘It’s a unique heritage,’ says Pierre Bouillon, throwing his musket and sword into the back seat of a Renault Clio, ‘but no-one else wants to celebrate it.’

The morning of the tribute – and the entire day – is a showcase of hilariously awful weather. Up at the Col de la Pierre St-Martin, it’s the opposite of July. Refreshment stalls are cocooned in frozen fog and the marquee that was to have housed the post-tribute festivities has been largely demolished by a ferocious overnight hailstorm.

‘Apocalyptique!’ calls a voice from beneath the capacious hemisphere of a rattan and canvas shepherd’s umbrella. Yet it’s a testament to the resonance of this event that around 1,000 people are milling about on a midweek non-holiday. Most are Spanish. Later I suggest to a Roncal farmer that on his side of the border there’s a stronger need to reconnect with vanishing rural traditions that are still part of life in the Barétous valley. He nods thoughtfully, then says: ‘No, we just like to party.’

At the appointed hour, dignitaries gather around the hallowed border stone. The Roncales stand resplendent in their traditional outfits: red-trimmed capes and broad hats for the men, ruched skirts and what look almost like matador jackets for the women. Tricolour sashes add a dash of colourful nobility to the humbler outfits worn by Pierre and his colleagues. Hands are stacked on the wet granite stump, and the ancient rubric rings out: ‘Pax avant! Pax avant! Pax avant!’ (in effect, ‘So let there be peace!’). For a moment time stands still, then applause and cheers fill the fog, underscored by the clonking moos of two dozen blondes d’Aquitaine crammed into a roadside pen for adjudication. A vet vaults the barrier and bravely parts bovine jaws for the cameras, veiled in hot breath and cold mist. It’s an honour for a Barétounais farmer to have his cows chosen, but as I’d been slightly saddened to discover the day before, the selection is now mere ceremony. ‘Four towns share the three-cows tribute,’ says Raquel Marco Landa, Isaba’s deputy mayor, ‘so the maths were always difficult.’ It’s now 15 years since any cattle changed hands; the good news is that the entire cash sum which does is blown on the celebratory feast.

Elders file into the customs house for French wine and Spanish cheese, while their irrepressible citizenry do an accordion-led conga through what’s left of the marquee, gobbling handfuls of garlic-fried breadcrumbs. The stormthreatened feast has been hastily relocated to Isaba’s frontón, a sports hall where locals play Basque pelota. The mist thins on the drive down: in place of rolling green there is bleak, sheer grey; the forests beneath are of hardy, pointed pine. Halfway to Isaba, the road flattens and I pull in at the Queseria Borda Marengo, home to José Manuel Marco, 230 sheep and some spirited dogs. ‘Don’t stand there being barked at,’ says José, standing at the door in white wellingtons that match his goatee. ‘Let’s go inside, eat my cheese and tell lies.’

José’s kitchen table is soon buried in matured Roncal produce. Some of it is reminiscent of Jean-Marc’s brebis (‘Yes, similar – but of course superior!’), some is like nothing else on Earth. As we slice and chew, José confirms that on this side of the border, shepherding, and all old-school agriculture, is in steep decline. ‘There were plenty of shepherds when I started at 22, but now we’re just three, and the youngest is 46. There’s so much land for us down here that we don’t need to go up in the mountains any more.’ He picks up an elaborate boxwood spoon from the table. ‘I’m still milking sheep at 10pm, and when I finish my reward is to carve these by hand – young people just won’t live that life.’

José says he’s got too much on to attend this year’s tribute feast, but he’s a veteran of many gone by. ‘Before they built the mountain road in the 1970s, getting up there meant an overnight walk,’ he says. ‘Apart from the mayors, not many bothered and, if you did, you’d earned that bowl of stew – and a skinful.’ As a pair of sprightly Isaban octogenarians later confirm, those charged with ferrying the feast up the mountain often felt entitled to refresh themselves to dangerous excess en route.

Girdled by lofty crags and packed with cobbled alleys, Isaba feels extremely distant from the French towns just over its steep doorstep. Only 450 people call it home, and by the time I arrive most are already sat at trestle tables between the fronton’s echoing green walls. Courses come and go in a blur, made more blurry by endless mayoral toasts of Navarran wine and the sloe-flavoured liqueur patxaran, a source of ruination for many visitors. Isaba’s mayor, Angel-Luis de Miguel, talks me through the centrepiece dish, caldereta – a hearty mutton stew that has fuelled shepherds on both sides since before the treaty was signed.

A band launches into the first of many accordion-heavy Basque favourites, but Angel-Luis is reluctant to align himself with the separatist movement, or to trouble his guests with the hacking ‘Zs’ and ‘Xs’ of Europe’s oldest language. ‘Me and Pierre,’ he says, raising a glass at his friend across the table. ‘We’re not French, Spanish or Basque. We are men of these valleys and mountains. The tribute is one day a year, but our hands are always on that stone.’

The article 'France and Spain’s centuries-old celebration of peace' was published in partnership with Lonely Planet Magazine.