Fig 3. Political constellation in Central Europe, early 10^th century.

The approx. borders between the Kingdom of Burgundy, Duchy of Svabia and Lombardia are indicated in red color. The Rhine, Rhône, Reuss and Aare rivers have their origin in the central Alps of Switzerland. The Rhine river runs through Lake Constance and continues in a northerly direction to the North Sea. The Rhône river runs through the Valais (S1 Fig), continues through Lake Geneva and then flows through the Rhône valley before joining the Mediterranean Sea. The Reuss river flows into the Aare river, which then joins the Rhine river.