When did polyphony start to become important for sacred and secular music?

The musicians of the region of the Balkans sang a music called Polyphonic, that had traditional Greek roots. The English Protestants began to include that type of music in their churches, also using the traditional instruments that the musicians of the Balkans used. Over time, this music is no longer used in churches, but in the southern parts of the United States is still used, and still heard in countries such as the United Kingdom, New Zealand and Ireland. The name means many voices, translated from the Greek Poly - many - and Phonic - voices.