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
Brandenburg stone Brandenburg stone The Brandenburg stone is an inscribed stone slab found in Brandenburg, Kentucky, United States in 1912, on the farm of Craig Crecelius. The stone contains a strip of linear markings that resemble letters of a script. Crecelius exhibited the stone several times, but was unable to find anyone who could identify the markings. Jon Whitfield, who acquired the stone in 1965, claims that they are Coelbren, a Welsh-language alphabet. Other writers have elaborated on these claims, arguing that this is evidence of pre-Columbian contact between the legendary Welsh prince Madoc and Native Americans. The consensus of Welsh scholars