There's no definitive history behind Christmas caroling. Where they originated, who wrote them and how they evolved is unclear. Caroling is an oral tradition, passed down from generation to generation.
Carols commemorating the nativity, or birth of Jesus Christ, were purportedly first written in Latin in the 4th and 5th centuries, but they didn't become associated with Christmas until the 13th century. Saint Francis of Assisi, the Roman Catholic saint of animals and the environment, is often credited with incorporating upbeat Latin hymns into Christmas services. The energetic, joyful carols were sung in sharp contrast to the somber Christmas music of the day. The concept of Christmas carols, and spreading them to the community to celebrate Christ's birth, is thought to have spread across Europe.