During the storm surge of the year 838, a significant part of the northwestern Netherlands, at that time part of the Frankish Empire, was flooded on December 26. In East Friesland this created the Leybocht, a sea arm near the city of Norden. An important cause of this disaster was the lack of proper dikes. The storm surge is recorded in the annals of the French bishop Prudentius of Troyes, and in the so-called Annales Xantenses, a Carolingian writing. Both sources describe major floods resulting in the destruction of a large number of places.