centuries in Basel (documented in 346), Martigny (doc. 381, moved to Sion in 585), Geneva (doc. 441), and Chur (doc. 451). There is evidence from the 6th century for a bishopric in Lausanne, which may have been moved from Avenches. With the fall of the Western Roman Empire, Germanic tribes moved in. Burgundians settled in the Jura, the Rhône valley and the Alps south of Lake Geneva; while in the north, Alamannic settlers crossed the Rhine in 406 and slowly assimilated the Gallo-Roman population, or made it retreat into the mountains. Burgundy became a part of the Frankish kingdom in 534; two years later, the dukedom of Alemannia followed suit. The Burgundy kings furthered the Christianization through newly founded monasteries, e.g. at Romainmôtier or St. Maurice in the Valais in 515. In the Alaman part, only isolated Christian communities continued to exist; the Germanic faith including the worship of Wuodan was prevalent. The Irish monks Columbanus and Gallus re-introduced Christian faith in the early 7th century. The Bishopric of Konstanz also was founded at that time. Switzerland in the Middle Ages Early Middle Ages Under the Carolingian kings, the feudal system proliferated, and monasteries and bishoprics were important bases for maintaining the rule. The Treaty of Verdun of 843 assigned the western part of modern Switzerland (Upper Burgundy) to Lotharingia, ruled by Lothair I, and the eastern part (Alemannia) to the eastern kingdom of Louis the German that would become the Holy Roman Empire. The boundary between Alamania, ruled by Louis, and western Burgundy, ruled by Lothar, ran along the lower Aare, turning towards the south at the Rhine, passing west of Lucerne and across the Alps along the upper Rhône to Saint Gotthard Pass. Louis the German in 853 granted his lands in the Reuss valley to the monastery of St Felix and Regula in Zürich (modern day Fraumünster) of which his daughter Hildegard was the first abbess. According to legend this occurred after a stag bearing an illuminated crucifix between his antlers appeared to him in the marshland outside the town, at the shore of Lake Zürich. However, there is evidence that the monastery was already in existence before 853. The Fraumünster is across the river from the Grossmünster, which according to legend was founded by Charlemagne himself, as his horse fell to his knees on the spot where the martyrs Felix and Regula were buried. When the