The Bavarian state-owned brewery Weihenstephan , located outside Munich since monks began brewing there in 1040, has a new hefeweissbier .

Don’t say you can’t teach an old brewery new tricks. Turning 1000 years old in 2040, the planet’s longest-operating brewery is partnering with America’s longest-operating 21st-century craft brewery to produce a first-of-its-kind collaboration.

Bavarian state-owned brewery Weihenstephan, located outside Munich since monks began brewing there in 1040, invited Sierra Nevada Brewing to Germany to brew a hoppy wheat beer scheduled to arrive on American shores in a one-time release in April. 63-year-old Sierra founder Ken Grossman, a self-taught former hippie who worked as a bike shop mechanic before brewing professionally, opened Sierra Nevada in in the Northern California town of Chico in 1980.

Though Grossman’s company, which helped pioneer the heavy use of hops associated with American craft brewing, could be considered an upstart when compared to the tradition-bound German stalwart, Sierra has notably outlived every one of the small handful of post-Prohibition “micro” breweries that opened before it. Grossman’s staunch dedication to independence and quality has earned his family-owned brewery the highest level of respect from worshipful brewers and drinkers worldwide.

That’s why when Weihenstephan’s export sales director, Marcus Englet, wanted to find the first brewer to visit him in the Old Country to collaborate, he turned to Sierra.

“This is not only a meeting of old and new worlds it’s a meeting of two foundation stones of brewing,” he told American and German beer writers in January inside a hundreds-of-years-old brick chapel that now serves as his brewery’s tour center.

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Though the hefeweissbier—called “Braupakt,” or “Brewery Pact"—uses the German Hallertauer hop and the West Coast Amarillo and Chinook varieties, it still complies with the 500-year-old Bavarian purity law that limits beer ingredients to water, malt, hops and yeast. It would have to, to be legally sold in Germany. The yeast strain, which lends apricot and banana notes, is the one developed by Weihenstephan years ago for its flagship Weihenstephaner hefeweissbier – the same one Sierra uses as its house wheat ale yeast.

“It’s a great honor and a great opportunity to partner with one of the most famous breweries in world,” says Scott Jennings, head brewer at Sierra’s Asheville, NC annex, who brewed on behalf of his boss.

Jennings will partner with Weihenstephan Brewmaster Tobias Zollo again over the summer, this time in Asheville, to jointly produce an Oktoberfest to follow in Sierra’s tradition of brewing an Oktoberfest with a different German brewer every year. Eight years ago, Weihenstephan brewers traveled to Boston to brew Infinium sparkling ale with colleagues employed by another early craft beer legend, Samuel Adams founder Jim Koch. But Braupakt marks the first time the Weihenstephan team has collaborated on its own turf.

But why would a brewery so steeped in history and located in the most restrictive beer-brewing region in the world want to partner with an American craft brewery in the first place?

Answers Zollo, “Standing still is stepping back.”

Though Zollo says he may pick up additional partners in the future, this doesn’t look to be the beginning of a radical departure from Weihenstephan’s steady course; as in, don’t expect him to start hooking up with any old (or, more accurately, new) maverick. “The traditions and values of quality are what we share with Sierra Nevada,” he says.