Short answers, pulled from the story.
The Hanseatic League, commonly called the Hansa, was a medieval commercial and defensive network of merchant guilds and market towns in Central and Northern Europe. It grew from Lübeck and a few other North German towns in the late 12th century and dominated maritime trade in the North and Baltic Seas.
The Hanseatic League effectively ended in 1669, when its last formal meeting, a Hanseatic Day called in Lübeck, drew only a few cities. The League never formally disbanded; it silently disintegrated. Hamburg, Bremen, and Lübeck remained as members until the formal end in 1862.
At its height the Hanseatic League encompassed nearly 200 settlements across eight modern-day countries. The network of alliances grew to include a flexible roster of 70 to 170 cities, ranging from Estonia and Russia in the northeast to the Netherlands in the west.
The four principal foreign trading posts, called Kontors, were the Steelyard in London, Bryggen in Bergen, the Kontor at Bruges in Flanders, and the Peterhof at Novgorod. Each was an extraterritorial enclave with its own treasury, court, legislation, and seal.
The Hanseatic League used economic force rather than a standing army, calling embargoes, blockading ports, and boycotting whole countries. It blockaded Novgorod in 1268 and 1277 and 1278, and boycotts against Norway in 1284 and Flanders in 1358 nearly caused famines. It lacked a permanent administrative body, a treasury, and a standing military force.
The Hanseatic League traded beeswax, furs, timber, resin, flax, honey, wheat, and rye from the east to Flanders and England, taking cloth, especially broadcloth, in return. Salt, herring, copper, iron, stockfish, and hopped beer were also central to its commerce.
The cog was the most emblematic Hanseatic ship, a clinker-built vessel with a carvel bottom, a stern rudder, and a square rigged mast. It could carry a cargo of about 125 tons and was depicted on many seals and coats of arms of Hanseatic cities. The hulk began to replace it by 1400.