Brandenburg Concerto No. 5 "Brandenburg Concertos" takes a central place. Nonetheless around half a dozen of Bach's extant concertos, including some of the "Brandenburg Concertos" and lost models of his later harpsichord concertos, seem to have had their roots in his Weimar period. Most of what Bach may have left with his employer in Weimar perished in a fire destroying Schloss Weimar in the 1770s. In 1719 a new large two-manual harpsichord arrived in the residence of Bach's then-time employer at Köthen. BWV 1050a, an extant early version of the fifth "Brandenburg Concerto", may have been conceived for this instrument, but that seems unlikely
Organ concertos, Op. 4 (Handel) of his oratorios Esther and Athalia. During this period Handel prepared the 16 movements of the four organ concertos HWV 290-293, of which 10 are reworkings of previous compositions with the remaining 6 largely newly composed. HWV 292, completed in March 1735, contains the most new material, although even there the ritornello of the first movement is a borrowing from Act 1 of Alcina. It featured in the April performances of Athalia at Covent Garden. The other concertos were first heard in March, HWV 290 and 291 in Esther and HWV 293 in Deborah. Handel completed Alexander's Feast in January