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.