Gregorian chant
From Conservapedia
Gregorian chant, and its close cousin, Old Roman chant, were a repertory of ritual melodies, possibly influenced by the equivalent music in the Jewish liturgy, in the first few centuries of the Christian church. Much of it survives in manuscripts of the 11th to 13th centuries. Whilst originally thought to be the style of chant used in Rome during Gregory’s ministry (590-604 A.D.) it is now believed to have originated in the Frankish Empire during Charlemagne’s reign when Roman liturgy was introduced there.
It began to be replaced by polyphony as a musical style in services during the High Middle Ages.
