Musical instruments have been in use for millennia, but their place in the music of the Middle Ages and Renaissance was often sharply defined and restricted. In the view of the Mediæval church, the human voice was an instrument created by God, and thus more able to sing His glories than instruments created by people. Because of this view, sacred music was predominantly vocal music.
Instrumental music already had a long history, and in some cultures was at least as important as vocal music, but popular instrumental music especially suffered from being regarded as "pagan". Inasmuch as many folk tunes likely predate the spread of Christianity, this was not an unreasonable view.
During the Middle Ages, instrumental music was most often an accompaniment: it accompanied voice, it accompanied dance, it accompanied ceremony, and it accompanied war. Only toward the end of the Renaissance did instrumental music "for its own sake" become common, and even the people of that era might have been astonished at the crowds attending concerts in the age of Beethoven or even Mozart.
Music in the early Middle Ages was largely monophonic. When several instruments played together, they probably took turns, or else played in unison or in octaves. As polyphony developed, so did the idea of a musical ensemble: instruments chosen because they blended well. Especially among the wind instruments, there were two types of ensembles, loud (haut) and soft (bas),