In his Getica, the chronicler Jordanes writes: "That area of the Swabians has the Bavarii in the east, the Franks in the west ..." Agilolfings Until the end of the first duchy, all rulers descended from the family of the Agilolfings. The Bavarians then colonized the area from the March of the Nordgau along the Naab river (later called the Upper Palatinate) up to the Enns in the east and southward across the Brenner Pass to the Upper Adige in present-day South Tyrol. The first documented duke was Garibald I, a scion of the Frankish Agilolfings, who ruled from 555 onward as a largely independent Merovingian vassal. On the eastern border, changes occurred with the departure of the West Germanic Lombard tribes from the Pannonian basin to northern Italy in 568 and the succession of the Avars, as well as with the settlement of West Slavic Czechs on the adjacent territory beyond the Bohemian Forest at about the same time. At around 743, the Bavarian duke Odilo vassalised the Slavic princes of Carantania (roughly corresponding with the later March of Carinthia), who had asked him for protection against the invading Avars. The residence of the largely independent Agilolfing dukes was then Regensburg, the former Roman Castra Regina, on the Danube river. During Christianization, Bishop Corbinian laid the foundations for the later Diocese of Freising before 724; Saint Kilian in the 7th century had been a missionary of the Franconian territory in the north, then ruled by the Dukes of Thuringia, where Boniface founded the Diocese of Würzburg in 742. In the adjacent Alamannic (Swabian) lands west of the Lech river, Augsburg was a bishop's seat. When Boniface established the Diocese of Passau in 739, he could already build on local Early Christian traditions. In the south, Saint Rupert had founded in 696 the Diocese of Salzburg, probably after he had baptized Duke Theodo of Bavaria at his court in Regensburg, becoming the "Apostle of Bavaria". In 798 Pope Leo III created the Bavarian ecclesiastical province with Salzburg as metropolitan seat and Regensburg, Passau, Freising and Säben (later Brixen) as suffragan dioceses. Carolingians With the rise of the Frankish Empire under the Carolingian dynasty, the autonomy of the Bavarian dukes, previously enjoyed under the Merovingians, was reduced and subsequently terminated. In 716 the Carolingians had incorporated the Franconian lands in the north, formerly held by the Dukes of Thuringia, whereby the