Wikipedia
Dengaku (田楽) were rustic Japanese celebrations that can be classified into two types: dengaku that developed as a musical accompaniment to rice planting observances and the dengaku dances that developed in conjunction with sangaku. The dengaku celebrated for rice planting was performed by villagers either at the New Year or during the planting season in early summer. It was only in the 14th century that these dances were brought to the cities and incorporated into Noh theater, notably by the playwright and actor Kan'ami. The instrument of dengaku is the sasara, a wooden percussive instrument clapper, though there are other instruments that can be used.
In the Eiga Monogatari there is a detailed description of the rice-planting dengaku. After being brought to the aristocrats, dengaku flourished till the end of the Heian period and became the main performing art of the Kamakura and part of the Muromachi period.
By the end of the Muromachi, dengaku was eclipsed by sarugaku. Today it barely survives as a folk performing art.
Dengaku was closely linked with the native Japanese religion of Shinto. Ritualistic elements of this was incorporated with Sarugaku to form Noh theatre.