The now-secularised St Peter's Church at Petersberg Citadel, Erfurt, where Henry the Lion submitted to Barbarossa in 1181
The Duchy of Saxony was originally the area settled by the Saxons in the late Early Middle Ages, when they were subdued by Charlemagne during the Saxon Wars from 772 and incorporated into the Carolingian Empire (Francia) by 804. Upon the 843 Treaty of Verdun, Saxony was one of the five German stem duchies of East Francia; Duke Henry the Fowler was elected German king in 919.
Stem duchies of the German kingdom 919–1125, by William R. Shepherd: Saxony in yellow, Franconia in blue, Bavaria in green, Swabia in light orange, Lower Lotharingia in dark pink, Upper Lotharingia in light pink, Thuringia in dark orange and Frisia in light orange