Wulfstan sailed from Hedeby (Haithabu), Jutland to Truso in seven days keeping Weonodland ("Wendland") on the right as far as the mouth of the Weissel (Vistula).
In the Viking period the route Eider - Treene - Rheider Au - Schlei served as a navigation way and/or transport or trade route between places to the north and the Baltic Sea, as commercial centres functioned (see Dorestad, Haithabu).