Earlier this month, leaders from the Three Seas Initiative converged in Bucharest to reinforce their commitment to the two-year-old alliance. The Three Seas Initiative, which links the 12 countries along the Baltic Sea, the Adriatic Sea, and the Black Sea, is a grand initiative indeed. As Croatia’s President, Kolinda Grabar-Kitarovic, said at the Bucharest summit, its ambition is to “make Central Europe the backbone of European resilience.”

Here’s the thing: Grand alliances are not doing too well these days. Tension is rife in both NATO and the European Union. A better example of multinational collaboration is, in fact, to be found among one of those three seas. The countries along the Baltic Sea have built not one overarching alliance but a patchwork of cooperation. Their pragmatic approach should be replicated by other regions of Europe and beyond.

In 1161, a German duke named Henry the Lion decided that the bloody battles between merchants from his North German empire and their competitors on the Swedish island of Gotland had to cease. Henry the Lion had realized that with peace in place, both sides would prosper—so he instituted an agreement that granted the Gotlanders the same rights as domestic merchants in his own dominions. Thus was born the Hanseatic League, one of the most successful alliances in history.

The name Hanseatic League was informally claimed several years ago by a group of northern EU member states, led by the United Kingdom. But it’s barely more than a label. Today’s de facto Hanseatic League is instead a modern incarnation of Henry the Lion’s creation: a cooperation patchwork between the tiny Baltic states and a few near neighbors. One outgrowth of this cooperation is the Nordic-Baltic Eight (NB8), a foreign policy coordination group comprising the five Nordic and three Baltic states. When Ojars Kalnins, a Chicago-bred Latvian MP and member of NB8, recently visited Washington, almost none of the legislators he spoke to had heard of the NB8. “But when I told them about it they were blown away,” Kalnins told me.

Indeed, thanks to groupings like NB8, Baltic Sea countries have achieved an extraordinary degree of cooperation. “The Baltic Sea region has never been as integrated as it is now,” noted Marko Mihkelson, an Estonian MP. The Baltic states and four of the Nordic countries, along with Britain and the Netherlands, recently launched the Joint Expeditionary Force, a 10,000-strong force that can be deployed on short notice. The Nordic-Baltic Mobility Fund supports cross-border artistic projects in the region. In honor of the three Baltic states’ 100^th independence anniversaries earlier this year, the Swedish government launched a cultural exchange fund. Ministers regularly meet to coordinate their countries’ policies on trade, foreign affairs, defense and transport. It helps that the neighbors have similar political cultures and objectives. There’s even a Baltic Sea Philharmonic for the region’s best young musicians—though it’s a private initiative funded by NordStream, the controversial Russian-backed energy venture.

Though Henry the Lion hadn’t planned to build a regional alliance, two centuries after his bold move the Hanseatic League comprised most of the Baltic Sea region, stretching from today’s Netherlands to Estonia, even as far south as Krakow. The League waged the occasional war, but it was primarily an economic alliance, forging trade deals with other parts of Europe, and sometimes even staging blockades.

Admittedly, neither the medieval League nor today’s Baltic Sea countries have achieved the perfect union. The Baltic states differ significantly from one another, Estonia essentially a one-nation Silicon Valley while Lithuania features a traditional manufacturing sector. The countries have strong disagreements on asylum policy. The Baltic Sea itself is dangerously polluted. But in an age where political tensions are growing, and where NATO and the European Union struggle to maintain unity, the region is a rare success story. “Our countries are likeminded, and we’re geographically and culturally close,” Kalnins pointed out.

And precisely because they’re likeminded, the countries cooperate on top of treaty arrangements by, for example, informally sharing threat updates. Through such constant contact and sharing, the neighbors have created an informal security bloc whose unity in itself functions as a deterrent against Russia. And the cooperation is a complement, not a threat, to larger alliances like NATO and the European Union. In fact, EU authorities are actively encouraging such cooperation, as seen in the European Commission’s agreement to co-finance the Baltic states’ planned joint railway, Rail Baltica.

The lesson from Henry the Lion and the Baltic Sea region in the 21^st century is this: A bloc doesn’t need federal or supranational ambitions in order to be successful, and it doesn’t need a large number of members. Indeed, in an age where citizens are wary of distant institutions and large alliances struggle under the weight of their diverse membership, the Baltic Sea region’s pragmatic model of a cooperative patchwork between likeminded countries has potential for other regions where neighbors are united by regional threats and opportunities. “The Nordic-Baltic example can be applied at least in part to other regions,” said Azita Raji, a former U.S. Ambassador to Sweden. “The Visegrad states [Poland, Hungary, Czech Republic, and Slovakia] have the potential to develop regional cooperation along similar lines.” Or imagine a Mediterranean version of the Hanseatic League.

The Three Seas Initiative is laudable. Making Central Europe the backbone of resilience: Who could argue with such an ambition? But an ambitious plan has to be filled with content agreed to by all its members. While the Initiative deserves every success, the countries around the Adriatic and Black Seas may find there’s considerable potential in deeper, Baltic Sea-style cooperation with their closest neighbors.

Like siblings, neighbors are often plagued by competitiveness. But if the perennially competitive Sweden and Norway can successfully team up in a 21^st-century Hanseatic League, other neighbors should be able to do the same. And as Henry the Lion knew, cooperation can thrive without grandiose beginnings. It just needs a common purpose.