Gayo's Saman Dance - Synchronized Headbanging

North Sumatra, South East Aceh in the Gayo highlands is an area of origin of the unique Saman dance. The dance was originally danced by 10 men, without the accompaniment of musical instruments. The musics produced by the voice of two group leader (syekh), clappinghands and pat chests. The lyrics are about islamic preach, ethics, epic etc. Syekh tasked also to give command of motion changes. This dance reportedly discovered and developed by Sheikh Saman, a scholar Gayo, although I think this dance seems older than that.