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
Twelve Concertos, Op. 7 (Vivaldi) Twelve Concertos, Op. 7 (Vivaldi) A set of twelve concertos was published by Estienne Roger in 1716-1717 under Antonio Vivaldi's name, as his Opus 7. They were in two volumes, each containing concertos numbered 1-6. Of the set, ten were for violin solo; the other two were for oboe solo. The authenticity of some of the works included has long been doubted by scholars. Three are now considered spurious (i.e. not in fact by Vivaldi) for stylistic reasons. They are: No. 1 in B-flat major for oboe, RV Anh. 143 (formerly RV 465); No. 7 in B-flat major for oboe,