What's the earliest known piece of polyphonic music?

Question

Do we know what is the earliest known piece of polyphonic music? I know that there are some 12-th century composers like Léonin and Pérotin that did this kind of thing, but did they compose the earliest known piece of polyphonic music?

Answer 1

New research has uncovered the earliest known piece of polyphonic music: a piece of choral music in two parts found in a British Library manuscript in London. This music that combines more than one melody is a short chant dedicated to Boniface, patron Saint of Germany. The inscription dates back to the 10th century and was inked into the space at the end of a manuscript of the Life of Bishop Maternianus of Reims.

Answer 2

According to Richard Taruskin in the latest Oxford History, polyphonic music probably existed for a very long time before it was written down. This is based upon written descriptions of musical performances. However the earliest KNOWN piece would have to be associated with the earliest notated polyphonic music. This would be before Leonin and Perotin (13th Century). "Parallel organum" was practiced in Europe in the 9th Century, for example.