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
Piano concertos by Wolfgang Amadeus Mozart the concertos in recent years, notably by Philips and Naxos, some of the less-well known concertos may also increase in popularity. The first four concertos are only orchestrations of works by other composers; Gutmann calls these "juvenilia." Gutmann also calls "simplistic" the Concerto for three (or two) pianos and orchestra. With these exceptions, Gutmann writes of Mozart that "all of his mature concertos have been acclaimed as masterpieces". For example, he says Mozart liked his first original concerto, his fifth (K. 175), written at age 17, and performed it through the rest of his life. The discography for Mozart's piano