Duchy of Westphalia
The name of Saxony derives from that of the Germanic confederation of tribes called the Saxons. Before the late medieval period, there was a single Duchy of Saxony. The term "Lower Saxony" was used after the dissolution of the stem duchy in the late 13th century to disambiguate the parts of the former duchy ruled by the House of Welf from the Electorate of Saxony on one hand, and from the Duchy of Westphalia on the other.