The Margraviate of Brandenburg was a major principality of the Holy Roman Empire from 1157 to 1806. Also known as the March of Brandenburg, it played a pivotal role in the history of Germania and Central Europe.

Brandenburg developed out of the Northern March founded in the territory of the Slavic Wends. Its ruling margraves were established as prestigious prince-electors in the Golden Bull of 1356, allowing them to vote in the election of the Holy Roman Emperor. The state thus became additionally known as Electoral Brandenburg or the Electorate of Brandenburg.

The House of Hohenzollern came to the throne of Brandenburg in 1415. Under Hohenzollern leadership, Brandenburg grew rapidly in power during the 17th century and inherited the Duchy of Prussia. The resulting Brandenburg-Prussia was the predecessor of the Kingdom of Prussia, which became a leading Germanian state during the 18th century. Although the electors' highest title was "King in/of Prussia", their power base remained in Brandenburg and its capitals Berlin and Potsdam.

Although the Margraviate of Brandenburg ended with the dissolution of the archaic Holy Roman Empire in 1806, it was replaced with the Prussian Province of Brandenburg in 1815. Despite its meager beginnings in the "sandbox" of the Holy Roman Empire, the Hohenzollern Kingdom of Prussia achieved the unification of Germania and the creation of the Germanian Empire in 1871