The Crow Creek Massacre Site is a historical site that dates back to the 16th century It exists on what is now a portion of the Crow Creek Reservation, and is considered an important site to the people who live on the reservation.
The site of the Massacre itself is located right along the banks of the Missouri River (as seen in the picture on the right). The site is what remains of a village formed by a tribe of Central Plains villagers. It would seem that the village was constantly under threat from a neighboring tribe, or tribes, and had a lack of food as well as protection. The malnutrition is hypothesized due to the skeletons appearing to be protein and iron deficient. The neighboring tribe attacked the village whilst they were attempting to dig fortifications to help protect the village. What followed ended being a massacre of the entire village by their neighbors. It seems that the killing was particularly brutal, with a number of the skeletons showing signs of mutilation and trauma to limbs and skull. The site was discovered by archaeologists in 1978 and since then has been determined to be of importance to the history of the Crow Creek Reservation. It was deemed a historical site and is now protected under the the Native American Graves Protection and Repatriation Act (NAGPRA) .
Black Elk's thoughts on the Massacre at Wounded Knee
I believe that, when Black Elk said that the "Nation's hoop is broken and scattered", he was referring to whatever semblance of congruity there was between the tribes of the Lakota, Dakota and Nakota and the United States government was lost with the massacre. I imagine he was commenting on how the government was so offended and frightened by their customs that performing a simple ceremony lead to a massacre like that at Wounded Knee. The hoop or circle is also held in high regard in Native American culture, and the fact that the hoop that represents the circle of life and harmony to the tribes would be described as broken is a commentary in and of itself on the sad state of affairs for them. Stating that there is no center and that the sacred tree is dead would be, I imagine, another way of saying that all meaning in their lives was now questionable, and that he wasn't sure that they could recover or survive the current sate of affairs.
Sources
http://www.nebraskastudies.org/0200/frameset_reset.html?http://www.nebraskastudies.org/0200/stories/0201_0122.html
http://www.nebraskastudies.org/0200/frameset_reset.html?http://www.nebraskastudies.org/0200/stories/0201_0122.html