The document summarizes the Sundance ceremony of the Sioux people. Some key details: - The Sundance is one of the Sioux's most sacred rituals, held annually when the moon is full in June or July to remind people of their ignorance that comes and goes with the moon. - Dancers offer their bodies as a sacrifice for the people, piercing their breasts with buffalo bones attached to a tree via rawhide ropes, dancing until the ropes break free. - The all-night dance on the first night represents people in darkness of ignorance, with offerings made at dawn. Dancers are painted and purified before dancing and facing the sacred tree. - After dancing, the dancers