Following the Carolingian period, the feudal system spread throughout Switzerland, with monasteries and bishoprics playing key roles in governance. The Treaty of Verdun in 843 divided the region: western Switzerland (Upper Burgundy) went to Lotharingia under Lothair I, while eastern Switzerland (Alemannia) became part of the eastern kingdom of Louis the German, which would later evolve into the Holy Roman Empire. The boundary between these territories ran along the Aare, Rhine, and across the Alps to the Saint Gotthard Pass.
Monasteries played a key role in governance and local autonomy. In 853, Louis the German granted lands in the Reuss Valley to the Fraumünster Abbey in Zürich, whose first abbess was his daughter Hildegard. The abbey, along with others, enjoyed Reichsfreiheit (imperial immediacy), exempting it from feudal lords and fostering local autonomy. This independence attracted local communities to align with the abbey for greater freedom and reduced taxes.
The decline of Carolingian power in the 10th century left the region vulnerable to external threats. The Magyars destroyed Basel in 917 and St. Gallen in 926, while Saracen raids ravaged the Valais and sacked the monastery of St. Maurice by 939. Stability returned only after King Otto I’s decisive victory over the Magyars at the Battle of Lechfeld in 955, reintegrating Swiss territories into the empire. These events set the stage for growing monastic influence and local autonomy that would shape the region in the following centuries.
Alemannia and Upper Burgundy around 1000. Orange = Alemannia. Green = Upper Burgundy. © Marco Zanoli