Some of them were baptized; the territory which was afterwards known as the duchy of Normandy was ceded to them; but the story of the marriage of their chief Rollo with a sister of the king, related by the chronicler Dudo of Saint Quentin, is very doubtful.
THIETMAR (DIETMAR or Dithmar) of Merseburg (975 1018), German chronicler, was a son of Siegfried, count of Walbeck, and was related to the family of the emperor Otto the Great.
The chief authority for the reign is the chronicler Flodoard.
Probably Dante knew of him only from the chronicler as a persecuted philosopher.
They cited the old book as the source of the information.