Keyboard concertos by Johann Sebastian Bach left Weimar in 1717. Many of Bach's orchestral harpsichord concertos are adapted from a model with one or more violin solo parts. Several of these earlier models are extant. The oldest of these is Vivaldi's concerto for four violins, RV 580, published in 1711, model for Bach's concerto for four harpsichords, BWV 1065. Bach replaced the part of his fourth "Brandenburg Concerto", BWV 1049, composed in 1721 or earlier, by a harpsichord part when he reworked it to the harpsichord concerto BWV 1057. Bach's extant violin concertos BWV 1041–1043, two for a single violin soloist and one for two violin
Brandenburg Brandenburg Brandenburg (; , Lower Sorbian: "Bramborska", ) is a state of Germany. Brandenburg is located in the northeast of Germany covering an area of and has a population of 2.5 million residents, the fifth-largest German state by area and tenth-most populous. Potsdam is the state capital and largest city, while other major cities include Brandenburg an der Havel, Cottbus, and Frankfurt (Oder). Brandenburg surrounds the national capital and city-state of Berlin, which together form the Berlin/Brandenburg Metropolitan Region, the third-largest metropolitan area in Germany. Brandenburg borders the states of Mecklenburg-Vorpommern, Lower Saxony, Saxony-Anhalt, and Saxony, and an international border