To the Sioux, the suppression of the Sun Dance was a significant spiritual blow, for the Sun Dance was an annual religious festival that embodied the power and spirit of the Sioux as a people. Babies had their ears pierced that they might hear as human beings and be members of the tribe; young men and women met during the big encampment, which provided a time for courting and the arranging of marriages; both men and women participated in the Sun Dance itself in sacrifice that their prayers be heard and that the people prosper; religious dreamers performed their special ceremonies to cure the sick and bring blessings on the people. In short, the Sun Dance renewed all life in a spiritual sense. After public celebration of the Sun Dance was prohibited, life at the agencies ceased to have any meaning derived from religious traditions; the people were cut off from their past.
Also prohibited were the give-aways of property held a year after a person's death to insure that the soul of the deceased was properly ushered to the land of the dead. Judged inimical to household economy, the practice was outlawed without regard to its moral implications. Similarly, dancing of all kinds was frowned upon, the Indian agents setting the days when such social celebrations could occur. The effect of these measures was to drive native Sioux religious practices into the sphere of private family life, weakening the effectiveness of traditional religion to draw the Sioux together as a people.
Taken from Vestiges of a Proud Nation, Edited by Glen E. Markoe, Robert Hull Fleming Museum, 1986