The popular attribution of Gregorian chant to Pope Gregory the Great, who died in 604, does not hold up well against the manuscript evidence, since musical notation capable of recording melody in any detail did not exist for roughly two centuries after his lifetime, making it impossible for a repertoire fixed in his own time to have survived unchanged to the point where it was finally written down.
Musicologists instead trace the repertoire's consolidation to the Carolingian period, the eighth and ninth centuries, when Frankish kingdoms under Charlemagne and his successors worked to standardize liturgical practice across their territory, drawing on existing Roman chant traditions, older Gallican practice native to Frankish lands, and considerable Frankish editorial shaping, a process that produced something closer to a newly unified Franco Roman repertoire than a simple transcription of what Rome alone had been singing. Gregory's name likely became attached to this consolidated body of chant later, as a mark of papal and Roman authority lent to a repertoire that in its surviving written form is substantially a Frankish achievement. Early notation used neumes, graphic symbols indicating melodic direction without precise pitch, gradually developing over subsequent centuries into the four line and eventually five line staff notation that made chant, and later polyphonic music built from the same pitch vocabulary, reliably transmissible in written form for the first time in Western musical history.