'''four sonatas for keyboard and violin, K. 6-9''' are among his earliest works. These were composed by a budding Mozart between 1762 and 1764. They encompass several of Mozart's firsts as a composer: for example, his first works incorporating the violin, his first works with more than a single instrument, his first works in more than one movement and his first works in sonata form. In fact, previous to this, all his works had been short solo-pieces for the harpsichord.
Mozart would have been between 6 and 8 years of age when he composed these works; hence it is believed by many that it was written down for the boy by his father, Leopold: all four of these early sonatas are preserved in Leopold's handwriting.
All of Mozart's early violin sonatas are really keyboard sonatas with violin accompaniment, a fact which is made clear from the original title of the four sonatas K. 6-9: ''Sonates pour le clavecin qui peuvent se jouer avec l'accompagnement de violon'' (\u201cSonatas for the keyboard, which may be played with violin accompaniment\u201d). It is quite legitimate, therefore, to perform these works on a keyboard alone.
In composing these early sonatas, Mozart may have been influenced by the German keyboard player and composer Johann Schobert, who was living and working in Paris when the Mozarts arrived there in November 1763. Schobert, in fact, had already published a number of keyboard sonatas with violin accompaniment, which possibly served as models for the young Mozart.