The Standing Rock Sioux Tribe of North & South Dakota controls the Standing Rock Reservation (Lakota: Íŋyaŋ Woslál Háŋ), which straddles the border between North and South Dakota in the United States, and is inhabited by ethnic "Hunkpapa and Sihasapa bands of Lakota Oyate and the Ihunktuwona and Pabaksa bands of the Dakota Oyate," as well as the Hunkpatina Dakota (Lower Yanktonai). The Ihanktonwana Dakota are the Upper Yanktonai, part of the collective of Wiciyena. The sixth-largest Native American reservation in land area in the US, Standing Rock includes all of Sioux County, North Dakota, and all of Corson County, South Dakota, plus slivers of northern Dewey and Ziebach counties in South Dakota, along their northern county lines at Highway 20.

The reservation has a land area of 3,571.9 square miles (9,251.2 km²), twice the size of the U.S. State of Delaware, and has a population of 8,217 as of the 2010 census. There are 15,568 enrolled members of the tribe. The largest communities on the reservation are Fort Yates, Cannon Ball (both located in Northern Standing Rock) and McLaughlin (located in Southern Standing Rock).

Together with the Hunkpapa and Sihasapa bands, the Standing Rock Sioux Tribe is part of what was known as the Great Sioux Nation. The peoples were highly decentralized. In 1868 the lands of the Great Sioux Nation were reduced in the Fort Laramie Treaty to the east side of the Missouri River and the state line of South Dakota in the west. The Black Hills, considered by the Sioux to be sacred land, are located in the center of territory awarded to the tribe.

In 1874, in direct violation of the treaty, General George A. Custer and his 7th Cavalry entered the Black Hills and discovered gold, starting a gold rush. The United States government wanted to buy or rent the Black Hills from the Lakota people, but led by their spiritual leader Sitting Bull, they refused to sell or rent their lands. The Great Sioux War of 1876 was a series of battles and negotiations that occurred between 1876 and 1877, with the Lakota Sioux and Northern Cheyenne warring against the United States. Among the many battles and skirmishes of the war was the Battle of the Little Bighorn, often known as Custer's Last Stand, the most storied of the many encounters between the U.S. army and mounted Plains Native Americans. It was an overwhelming Native American victory. The U.S. with its superior resources was soon able to force the Native Americans to surrender, primarily by attacking and destroying their encampments and property. The Agreement of 1877 (19 Stat. 254, enacted February 28, 1877) officially annexed Sioux land and permanently established Native American reservations. Under the Agreement of 1877 the U.S. government took the Black Hills from the Sioux Nation.

In February 1890, the United States government broke another Lakota treaty by breaking up the Great Sioux Reservation, an area that formerly encompassed the majority of the state. It reduced it and divided it into five smaller reservations. The government was accommodating white homesteaders from the eastern United States; in addition, it intended to "break up tribal relationships" and "conform Indians to the white man's ways, peaceably if they will, or forcibly if they must". On the reduced reservations, the government allocated family units on 320-acre (1.3 km²) plots for individual households.

Although the Lakota were historically a nomadic people living in tipis, and their Plains Native American culture was based strongly upon buffalo and horse culture, they were expected to farm and raise livestock. With the goal of assimilation, in the late 19th and early 20th centuries, they were forced to send their children to boarding schools; the schools taught English and Christianity, as well as American cultural practices. Generally, they forbade inclusion of Native American traditional culture and language. The children were beaten if they tried to do anything related to their native culture.

The farming plan failed to take into account the difficulty that Lakota farmers would have in trying to cultivate crops in the semi-arid region of South Dakota. By the end of the 1890 growing season, a time of intense heat and low rainfall, it was clear that the land was unable to produce substantial agricultural yields. As the bison had been virtually eradicated a few years earlier, the Lakota were at risk of starvation. The people turned to the Ghost Dance ritual, which frightened the supervising agents of the Bureau of Indian Affairs. Agent James McLaughlin asked for more troops. He claimed that spiritual leader Sitting Bull was the real leader of the movement. A former agent, Valentine McGillycuddy, saw nothing extraordinary in the dances and ridiculed the panic that seemed to have overcome the agencies, saying: "The coming of the troops has frightened the Indians. If the Seventh-Day Adventists prepare the ascension robes for the Second Coming of the Savior, the United States Army is not put in motion to prevent them. Why should not the Indians have the same privilege? If the troops remain, trouble is sure to come."

Thousands of additional U.S. Army troops were deployed to the reservation. On December 15, 1890, Sitting Bull was arrested for failing to stop his people from practicing the Ghost Dance. During his arrest, one of Sitting Bull's men, Catch the Bear, fired at Lieutenant "Bull Head", striking his right side. He instantly wheeled and shot Sitting Bull, hitting him in the left side, and both men subsequently died.