Keyboard concertos by Johann Sebastian Bach soloists, were all adapted into harpsichord concertos by the composer, BWV 1058, 1054 and 1062 respectively. It is often assumed that Bach's extant violin concertos were written in his Köthen period (1717–1723): it can however not be proven from documentary evidence that any of them existed prior to around 1730. In September 1725 Bach performed organ music, accompanied by other instruments, in Dresden. The works he performed there have not been identified. More than a year later he composed several cantatas with an organ obligato part. Several movements of such cantatas were derived from earlier lost concertos, and resurfaced in
Margraviate of Brandenburg throne, as they already held the vote of Bohemia. Charles succeeded in purchasing Brandenburg from Margrave Otto for 500,000 guilders in 1373 and, at a in Guben, he attached (but not incorporated) Brandenburg to the Crown of Bohemia. The "Landbuch" ("land book", i.e. estate register) of Charles IV, a source for the history of medieval settlement in Brandenburg, originated during this time. Charles chose the castle of to be the electoral residence. The power of the Luxembourgs in Brandenburg declined during the reign of Charles's nephew Jobst of Moravia. The was pawned to the Teutonic Knights, who neglected the border