The historic principality of Brandenburg originated as a margravate, or mark, that was an electorate of the Holy Roman Empire. Brandenburg was the nucleus of the dynastic power on which the kingdom of Prussia was founded, and it was merged administratively with that kingdom in 1701.

The history of Brandenburg is a long and complex narrative of transformation from a Slavic frontier to the heart of the Prussian state. Originally inhabited by Germanic tribes and then Slavic Wends, the region was conquered in the 12th century by Albert the Bear, who established the Margraviate of Brandenburg. In 1356, it became one of the seven electorates of the Holy Roman Empire, granting its rulers the power to elect the Emperor. The rise of the House of Hohenzollern in 1415 began a centuries-long expansion, eventually leading to the union of Brandenburg and the Duchy of Prussia. Under the "Great Elector" Frederick William, the region emerged as a major military and political power in Europe, surviving the devastation of the Thirty Years' War. After the Napoleonic Wars, it was formally reorganized as a province of the Kingdom of Prussia in 1815. Following World War II, the region was split; its eastern territories were ceded to Poland, while the western part became a state in East Germany. After German reunification in 1990, Brandenburg was re-established as a federal state surrounding the capital city of Berlin, serving as a cultural and historical anchor for modern Germany.