Brandenburg Concerto No. 5 "Brandenburg Concertos" takes a central place. Nonetheless around half a dozen of Bach's extant concertos, including some of the "Brandenburg Concertos" and lost models of his later harpsichord concertos, seem to have had their roots in his Weimar period. Most of what Bach may have left with his employer in Weimar perished in a fire destroying Schloss Weimar in the 1770s. In 1719 a new large two-manual harpsichord arrived in the residence of Bach's then-time employer at Köthen. BWV 1050a, an extant early version of the fifth "Brandenburg Concerto", may have been conceived for this instrument, but that seems unlikely
Brandenburg the Province of Brandenburg, again subdivided into the government regions of Frankfurt and Potsdam. In 1881, the City of Berlin was separated from the Province of Brandenburg. However, industrial towns ringing Berlin lay within Brandenburg, and the growth of the region's industrial economy brought an increase in the population of the province. The Province of Brandenburg had an area of and a population of 2.6 million (1925). After World War II, the Neumark, the part of Brandenburg east of the Oder–Neisse line, was transferred to Poland; and its native German population expelled. The remainder of the province became a state