Friesland is a district (Landkreis) in Lower Saxony, Germany. It is bounded by (from the southeast and clockwise) the districts of Wesermarsch, Ammerland, Leer and Wittmund, and by the North Sea. The city of Wilhelmshaven is enclosed by, but not part of the district.
The Frisian region was ruled by local chieftains until the 15th century; see East Frisia for details.
In 1438 in the northern part of today's Landkreis Friesland the Lordship of Jever was founded. East Frisia was from then on regarded as a hostile territory, and lots of skirmishes between Jever and East Frisia took place during the 15th and 16th centuries. The last ruler of Jever was Mary of Jever, who ruled until 1575.
After her death Jever became a part of Oldenburg, but East Frisia made a claim for the territory as well. In the following decades East Frisia tried to block all roads between Jever and Oldenburg. It was not before the 17th century that the hostilities between East Frisia and Oldenburg ended.
The southern part of today's District of Friesland is the "Friesische Wehde" ("Frisian Woods"), which also was most of the time part of Oldenburg. This region later formed the District of Varel.
The District was established in 1933 by merging the former districts of Jever and Varel under the name of "Friesland". In 1977 it was dissolved and divided between the neighbouring districts of Wittmund and Ammerland. The dissolution was declared unconstitutional in 1979 because it violated the rights of the former State of Oldenburg, and the District was re-established in its old boundaries in 1980.
Friesland is also is a province in the northwest of the Netherlands.