The Sioux are a Native American tribe and First Nations band government in North America. The word Sioux may describe any ethnic group within the Great Sioux Nation or one of the numerous dialects of the nation. There are three parts of the Sioux based on language dialects and subcultures: the Santee, the Yankton-Yanktonai, and the Lakota.

There have been a number of armed conflicts between the people of the US and the Lakota, and the famous and still remembered massacre at Wounded Knee Creek was the last of them. It is also considered one of the key events in the history of the relationships between the two nations. The name "massacre" came from General Nelson A. Miles' letter to the Commissioner of Indian Affairs. It was fixed in history this way.

On December 29, 1890, five hundred troops of the U.S. 7th Cavalry, supported by four Hotchkiss guns (a lightweight artillery piece capable of rapid fire), surrounded an encampment of the Lakota bands of the Miniconjou and Hunkpapa with orders to escort them to the railroad for transport to Omaha, Nebraska. By the time it was over, 25 troopers and more than 150 Lakota Sioux, including innocent women and children, lay dead. It is still unknown who started the fire, as it everything is believed to have begun as a "friendly fire". Anyway, the conditions of the shooting were chaotic, that's why there is still no concrete answer to this question.

The event remains a well-known accident, often observed in popular culture. It is often remembered in many songs, poems and illustrations.

More Info: en.wikipedia.org