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
Province of Brandenburg the Bear, another Saxon count from the noble House of Ascania, who established the Margraviate of Brandenburg in 1157. His son Margrave Otto I already achieved the dignity of an Arch-Chamberlain of the Holy Roman Empire in 1177. Emperor Charles IV by the Golden Bull of 1356 confirmed the electoral dignity of the Brandenburg margraves and in 1373 assigned the electorate to his son Wenceslaus in 1373. The Elector of Brandenburg held the seventh rank among the electors of the Empire and had five votes in the Council of Princes. In 1415 Brandenburg was acquired by Burgrave Frederick of Nuremberg,