For a large part of the Catholic Church’s history, the fundamental music in every mass was Gregorian chant. This type of chant gets its name from Pope Gregory I, who is credited with hearing these melodies directly from God through a dove that perched on his shoulder. Not only does the story of its transmission leave us with a feeling of doubt, but Gregory died in 604, while the earliest evidence of Gregorian chant comes from the 10th century. It is now thought that Charlemagne had a great deal of influence in codifying the chant repertory during his life.
Prior to this codification, each region of Europe had its own chant repertory with slightly different features. Since Charlemagne’s codification, some of these regional chants are no longer decipherable, such as Mozarabic chant, native to areas of Spain.