Billung March

The Billung March (German: Billunger Mark) or March of the Billungs (Mark der Billunger) was a frontier region of the far northeastern Duchy of Saxony in the 10th century. It was named after the family which held it, the House of Billung.

The march reached from the Elbe River to the Baltic Sea and from the Limes Saxoniae to the Peene River in the east, roughly the territory of present-day eastern Holstein, Mecklenburg, and parts of Western Pomerania. German expansion into the region of the Billung March was "natural" and the settlement "true colonisation." This can be contrasted with the military occupation of the Marca Geronis, the great march of Gero to the south of the Billungs.

The Billung March was formed in 936, when Otto I, Duke of Saxony and King of East Francia, made Hermann Billung princeps militiae (margrave, literally "prince of the militia"), granting him control of the border with rule over the West Slavic Obotrite tribes, including the Polabians, Warnabi and Wagri, as well as the Redarii, Circipani, and Kissini tribes of the Veleti confederation, and the Danes, who had repeatedly campaigned the territory. Major parts of the land of the Liutizi and the Hevelli laid beyond Hermann's sphere in the Marca Geronis.