Sea salt
In 1260 Bremen joined the Hanseatic League. A trade cartel of northern European towns, it was centred upon Lübeck, a base for merchants from Saxony and Westphalia trading in the eastern Baltic. This was a source timber, wax, amber, resins, and furs, along with rye and wheat brought down on barges from the hinterland to port markets. Of equal importance to the powerful merchant guilds or "Hansa" of Bremen was the ability of the League to control of the North Sea salt-fish trade, especially the Scania Market.