N/Um Tchai: The Ceremonial Dance of the!Kung Bushmen (1969)
Tchai is the word used by Ju/'hoansi to describe getting together to dance and sing; n/um can be translated as medicine, or supernatural potency. In the 1950's, when this film was shot, Ju/'hoansi gathered for "medicine dances" often, usually at night, and sometimes such dances lasted until dawn.