In the old days, People have been putting instruments together in various combinations for as long as there have been instruments, Early Renaissance composers were writing a part but did not meant instruments.
Around 1600 in Italy, the composer Claudio Monteverdi. His opera Orfeo (1607), and he said exactly what instruments should play: fifteen viols of different sizes; two violins; four flutes, two large and two medium; two oboes, two cornetts (small wooden trumpets), four trumpets, five trombones, a harp, two harpsichords, and three small organs.