Summary
In the 11th century the counties in Mid-Frisia belonged to counts of the 'Brunonian' House, but it is unknown as to how they acquired authority in this part of the German kingdom. According to numismatic evidence, a count Wichmann, assumedly of the House of Billung, ruled in this area before the Brunonians. This fact, combined with historical knowledge, could help to solve the puzzle.
In this article it is demonstrated how members of the House of Billung inherited properties in Mid-Frisia and, hence, could possibly acquire the rights of a count there; and next, how a daughter of this House could be the wife of the first Brunonian count in this area, thus enabling the Brunonians to claim those rights.