Kecak dancers

Kecak is a form of Balinese music drama, originated in the 1930s and is performed primarily by men. Also known as the Ramayana Monkey Chant, the piece, performed by a circle of 100 or more performers wearing checked cloth around their waists, percussively chanting "cak" and throwing up their arms, depicts a battle from the Ramayana where monkeys help Prince Rama fight the evil King Ravana.
However, Kecak has roots in sanghyang, a trance-inducing exorcism dance.