The earliest documentary traces of Bach's involvement with the concerto genre include: Bach wrote most, if not all, of his concerto transcriptions for organ (BWV 592–596) and for harpsichord (BWV 972–987) from July 1713 to July 1714.
Other models for the transcriptions included concertos by Alessandro Marcello, Benedetto Marcello, Georg Philipp Telemann and Prince Johann Ernst of Saxe-Weimar.
[1] Bach's Italian Concerto, BWV 971, was published in 1735, as first of two compositions included in Clavier-Übung II.
[1] For organ: For harpsichord: For chamber ensemble: Orchestral concertos: Detailed accounts of possible or conjectural reconstructions of Bach's harpsichord concertos for other solo instruments have been described systematically in the hand-book of Siegbert Rampe.
Earlier versions for unaccompanied keyboard instruments of all three movements of the Triple Concerto, BWV 1044, are extant.
Other harpsichord concertos, and related cantata movements if available, have been the basis for several reconstructions.