Generally held in late spring or early summer, the Sun Dance gathered bands together after they had dispersed to better survive the winter. The significance of this ritual of sacrifice was the spiritual renewal of participants and their families in addition to the renewal of the earth and her resources. After a period of private reflection and preparation, dancers fasted during the three or four days of the communal ceremony. The dance sometimes involved voluntary torture at the climax of the dance, particularly among the Sioux and Cheyenne. Dancers were pierced through the breast or shoulder muscles and the skewers tied to a center pole. As they danced, they pulled away from the pole until their skin tore from their bodies. Participants hoped to attain supernatural aid and individual power through their suffering. Animal symbols, such as the eagle and the buffalo, played an important role in the ceremony. The U.S. government outlawed the Sun Dance in 1904, but contemporary tribes still perform the ritual, a right guaranteed by the 1978 American Indian Religious Freedom Act.