The instrumental music repertory kept in the music archives of Chiquitos (Archivo Musical de Chiquitos) consist of two major collections: a) music for an instrumental ensemble; b) keyboard music. Each of these contains approximately 200 works of music (either fragmentary or complete works). It is difficult to maintain that such a large number of works was to be found in each of the Jesuit settlements. It is possible that the musical libraries of the guaran settlements were even larger. Since these documents have disappeared altogether, we can neither confirm nor deny their existence. On the other hand, in the archives of the missionary post in Moxos, where 4000 sheets of music are kept, the instrumental works do not exceed 20 and are generally fragments of sonatas, concertos and dances. No instrumental music has been found, not even fragments. In among the quartets, dances, partitas, concertos, symphonies and sonatas belonging to the music collection of Chiquitos, the latter, numbering approximately 110 compositions, are the best known. In most cases, the copyist left no details regarding the composer. The ones of which the composer is mentioned or recognized by the musicologists that have studied the music collection of Chiquitos, were written by Arcangelo Corelli, Antonio Vivaldi, Niccol Jommelli, Ignazio Balbi, Pietro Locatelli, Giovanni Battista Sammartini, Nicola Calandro and Domingo Poretti. Ten sonatas that were attributed to Arcangelo Corelli make him the most popular and prolific composer of instrumental music in the ancient Jesuit missionary posts. On the other hand, no instrumental music has ever been found that could prove beyond any doubt that the composer.