The town subsequently joined the Hanseatic League.
About 1350 it joined the Hanseatic League.
Founded in the 10th century as Lowenwold, Uelzen became in the middle ages an active member of the Hanseatic League.
The assertion of Hanseatic influence in the two decades, 1356 to 1377, marks the zenith of the League's power and the completion of the long process of unification.
The decisive factor in determining membership in the League was the historical right of the citizens of a town to participate in Hanseatic privileges abroad.