Music and singing were important in England during the medieval period, being used in religious ceremonies, court occasions and to accompany theatrical works. Singing techniques called gymel were introduced in England in the 13th century, accompanied by instruments such as the guitar, harp, pipes and organ. Henry IV sponsored an extensive range of music in England, while his son Henry V brought back many influences from occupied France. Carols became an important form of music in the 15th century; originally these had been a song sung during a dance with a prominent refrain — the 15th century form lost the dancing and introduced strong religious overtones. Ballads were also popular from the late 14th century onwards, including the "Ballad of Chevy Chase" and others describing the activities of Robin Hood. Miracle plays were performed to communicate the Bible in various locations. By the late 14th century, these had been extended into vernacular mystery plays which performed annually over several days, broken up into various cycles of plays; a handful have survived into the 21st century. Guilds competed to produce the best plays in each town and performances were often an expression of civic identity.