Europe in 1300
Hanseatic League
Hansa means an association or league, so "Hanseatic League" is a bit repetitious, but that's how it's long been known in English (as an entirely trivial aside: Luft means air in German, so now you know why Lufthansa is called that).
The Hansa was a league of cities concentrated along the southern coast of the North Sea and Baltic Sea. Membership in the league was not strictly enforced, so it's difficult to say exactly how many cities were "in" the league. The league in fact was a kind of agglomeration of treaties between about sixty or eighty towns, with an agreement that disputes might be settled by "the league", which itself sometimes entered into treaty arrangements.
At core of the Hansa were two cities: Hamburg and Lübeck, situated respectively on the west and east side of the Danish peninsula. These two formed an alliance in 1241, which can be taken as the foundation year for the league. More and more towns made arrangements over the course of the 13th century, chief among which were Cologne and Danzig. Moreover, Lübeck negotiated treaties with England and other powers, and with individual cities, such as Bruges. The Hanseatic League was an economic league, primarily concerned with negotiating trade deals. The first formal Diet of the league was held in 1356, in Lübeck, which continued to be the leading city of the Hansa.
By then, the League was powerful enough that it was controlling most of the Baltic Sea trade, which in turn brought it into conflict with other powers, most notably Denmark, and a series of actual wars were fought. The League also fought with the Teutonic Knights and Poland. But the League was never about physical boundaries. It was always about trading rights, and colonies (called kontore) of Hansa merchants could be found far inland all across Europe, from London to Novgorod. Whenever our course looks toward northeast Europe, we'll have to take account of the Hanseatic League.