Here's the Wiki on it,
https://en.wikipedia.org/wiki/Ghost_Dance which totally takes the bias as looking at it as a religion only. I grew up in the West with Elders who remembered their fathers and Grandfathers during the American Indian wars finding themselves fighting spirits and some getting so spooked they refused to return to the battle field.
Whatever happened out there - it was scary enough to spook Military men and for it to become illegal to dance the Ghost Dance. Still. Just some interesting back history. It's always interesting when science either denies something or refuses to look at it but Federal Laws around the subject are enacted anyway.