Hanse, from low german
hansa, meaning the federation, also called the Hanseatic League.
Since the 12th or 13th century the Hanse was the name of a unification of German (mainly north german) merchants. It was founded from a need of mutual protection and assistance in foreign countries. Later the Hanse-cities took the place of the single merchants. At the end of the 13th century a complete (but loose) federation of all Hanse-cities was founded, under the Leading of the city of Lübeck. They had no form of constitution but the politics of the Hanse was formed by the representatives of the Hanse-Cities. The strongest support the Hanse found in the Deutscher Orden, which had similiar interests.
"Northern German mastery of trade in the Baltic Sea was achieved with striking speed and completeness in the late 12th and early 13th centuries. ... From Visby, German
merchants helped establish important towns on the east coast of the Baltic: Riga, Reval (now Tallinn), Danzig (now Gdansk), and Dorpat (now Tartu). Thus, by the early 13th century Germans had a near-monopoly of long-distance trade in the Baltic. In the meantime, merchants from Cologne (Köln) and other towns in the Rhineland had
acquired trading privileges in Flanders and in England." from britannica.com
The trade of the Hanse was possible because of a maritime and politicial superiority and the strong link to the german settlement at the east sea. For a long time the Hanse had a monopoly on trading in the east sea, England and Flanders (Holland).
When the trade was endangered the Hanse sent strong armys to protect their interests. In the 15th century the Hanse still operated militarily in England, Flanders and Denmark.
"The Hanseatic League's aggressively protectionist trading practices often aroused opposition from foreign merchants. The league typically used gifts and loans to foreign political leaders to protect its commercial privileges, and when this proved inadequate, it threatened to withdraw its trade and occasionally became involved in embargoes and blockades. Only in extreme cases did the league engage in organized warfare, as in the 1360s, when it faced a serious challenge from the Danish king Valdemar IV, who was trying to master the southwestern Baltic and end the league's economic control there. The league's members raised an armed force that defeated the Danes decisively in 1368, and in the Peace of Stralsund (1370) Denmark was forced to recognize the league's supremacy in the Baltic." taken from britannica.com
At its peak in the 15th century the Hanse had over 160 members. Members where spreaded from the lower rhine to Livland, from Stockholm to Krakau and Breslau. It had branch offices, factories and stores in cities (in foreign countries) like London, Oslo, Bergen and Nowgorod (Novogorod ?).
The founding of a united economy led to a vast growing of the cities in North- and East-Europe.
Later both English and Dutch Ships proceded to the east sea and in the 16th century they removed the advantages and special rights of the Hanse.
Today, some german cities still have the "Hanse" in their name like Hanse-Stadt (Hanse City of) Hamburg, Hanse-Stadt Bremen ec.