evidence: The Bay of Sielmönken or Bight of Sielmönken (German: Bucht von Sielmönken or Sielmönker Bucht) is a former bay on the territory of the present day municipality of Krummhörn in the west of East Frisia in Germany. The bight reached its greatest extent during the Carolingian transgression of 800 to 950 A. D.[1] After that it silted up heavily and was completely enclosed by dykes between 1,000 A. D. and the 13th century. Location [edit]The Bay of Sielmönken was situated between the Dollart and the Leybucht on the terrain of the present-day municipality of Krummhörn, with a small portion on the territory of Hinte. In the Early Middle Ages it separated the historical regions of Emsgau and Federgau.[2]