Nothing to do with sports, the Hanseatic League was an economic alliance of cities centred around the Baltic and North Sea coasts of Europe from the 13th century to the 17th century, specifically Northern Germany, Estonia, Latvia and Lithuania's modern borders. It began with an alliance between Hamburg and Lübeck, other key locations included Lüneburg, Bremen, Rostock, Danzig (now Gdańsk) and Riga, but also cities as far inland as Cologne, Berlin, Magdeburg and Krakow. Designed to provide protection for mutual economic interests, they established trading posts as far apart as London and Novgorod (not to be confused with Nizhny Novgorod). They provided protection against pirates, trained harbour pilots and had periodic diets (that's assemblies). They were pretty protectionist and liked to get monopolies (a common medieval practice), and sometimes engaged in military warfare. In their heyday in the 14th to 15th century, they for instance took Copenhagen several times and won a say in who sat on the Danish and Swedish thrones. When they declined, Danish king Frederik II had them kicked out of Bergen in Norway to get a hold of power there. Topping out about at 100 cities in the 14th century, the League gradually declined as its lack of central government (partly to avoid legal problems against a single entity) caused a problem against competition from Scandinavian merchants and the Dutch. Once America was opened up and thus trade across the Atlantic grew more important than trade across the Baltic, the death knell was sounded and the last diet was held in 1669. Its legacy lives on in a number of Dutch and German cities calling themselves "Hanseatic" (including the German states of Bremen and Hamburg, which have the official title of "Free Hanseatic City" and "Free and Hanseatic City" respectively). There is also the New Hanse, a voluntary association of cities that began in 1980.
In real life