Duchy of Swabia
During the 9th century and the 10th century Sundgau was administered by the Lieutfried family. Following the breakup of Charlemagne's empire, the region entered a period of instability, culminating in the emergence of feudalism. From 925 on, the Sundgau belonged to the Duchy of Swabia; it remained a part of Swabia until the Duchy disintegrated in the 13th century.