After the fall of the Western Roman Empire, Rome lost its position as a church center. At the end of the 6th century, Pope Gregory I (reigned from 59 to 64) began to rebuild the position of the Roman church center. While reorganizing the religious rituals and institutions of the church, from 59 to 64, he organized church personnel to select and compile songs such as liturgical songs and hymns used by various churches, presided over the formulation of the code of church music-Anthology, and sent messengers to churches all over Europe to order them to use them in liturgy. This is a classic music document in the Middle Ages, which collects songs that should be performed in church worship and Eucharist. There are two existing versions, one is a hymn with Frankish style in the period of Charlemagne, the Frankish king in the 8th-9th century; One is an ancient Roman version from the 11th to 13th centuries (according to research, it can be traced back to the 8th century AD).