Berlin is situated in, but is administratively separate from, Brandenburg.
A 1996 referendum on whether to merge the two entities into a single state was approved by residents of Berlin but rejected by voters in Brandenburg. Drained by the Havel, Spree, and Oder rivers, the region encompassed by the state has many lakes and pine forests. The Slavic principalities had been previously subdued by Charlemagne but had regained their independence. In the 10th cent. the German kings organized the North March, a small area on the Elbe, which was bestowed on Albert the Bear in 1134. Albert expanded his territory, and in 1150 he inherited the principality of Brandenburg from its last Wendish prince.