The concerto transcriptions of Johann Sebastian Bach date from his second period at the court in Weimar (1708–1717). Bach transcribed for organ and harpsichord a number of Italian and Italianate concertos, mainly by Antonio Vivaldi, but with others by Alessandro Marcello, Benedetto Marcello, Georg Philipp Telemann and the musically talented Prince Johann Ernst of Saxe-Weimar. It is thought that most of the transcriptions were probably made in 1713–1714. Their publication by C.F. Peters in the 1850s and by Breitkopf & Härtel in the 1890s played a decisive role in the Vivaldi revival of the twentieth century.

Despite the undeniable support he received from the Wilhelmsburg, Bach must have developed closer personal ties to the Red Palace. The young Duke Ernst August, who played both violin and trumpet and who was known for his active acquisition of musical instruments and performing materials for his large music library, paid Bach in 1711-12 for giving keyboard lessons to his page Adam von Jagemann (who also received dance instruction from Bach's colleague and landlord Weldig). The duke's twelve-year-old half-brother, Prince Johann Ernst, was taught the violin as a small child and, from 1707 on, studied keyboard and composition with Johann Gottfried Walther, the Weimar town organist and distant relative of Bach's (in 1708, Walther wrote an instruction manual, Praecepta der masicalischen Composition, for the prince and presented it to him as a nameday gift). Bach later transcribed four of the prince's compositions, for organ and harpsichord (BWV 592, 595, 982, and 987)." Carl Philipp Emanuel Bach reported to Forkel that along with Prince Leopold of Cothen and Duke Christian of Weissenfels, "Duke Ernst August in Weimar . . . particularly loved him, and rewarded him appropriately?". Whether or not the warmer relationship with Ernst August ultimately had a negative impact on Wilhelm Emu's attitude toward Bach, a sizable salary supplement for his final Weimar years was covered by the younger duke's treasury.'; Bach's double function as court organist and chamber musician reflects his versatility and expertise as a performer, but increasingly as a composer, too. As a member of the court capelle, he belonged to the group of "joint servants" and was therefore employed by both dukes and paid by the joint treasury. In 1708-9, Bach's first year, the capelle consisted of twelve mostly full-time members".

In this, the Keyboard Concerto no. 14 in D Minor (BWV 987) Bach created a transcription after after one of the 6 Violin Concertos, Op.1, by Prince Johann Ernst of Saxe-Weimar.

Source: Wikipedia (https://en.wikipedia.org/wiki/Concerto_transcriptions_ for_organ_and_harpsichord_(Bach))

Although originally written for Harpsichord. I created this Arrangement of the Concerto in D Minor (BWV 987) for Viola & Concert (Pedal) Harp.