Polyphony is a characteristic of Western music.

It began when singers started improvising with parallel melodies, with emphasis on fourth (ex. C to F) and fifth (ex. C to G) intervals." target="_blank" class="inline-link">https://www.liveabout.com/... This marked the start of polyphony wherein several musical lines were combined.

As singers continued experimenting with melodies, polyphony became more elaborate and complex.