In 1876, Sitting Bull and about 4,000 Sioux (Dakota) warriors arrived in the Cypress Hills area from the United States after their defeat of the army of General George Custer at the Battle of Little Big Horn. They feared American reprisals and came to Canada requesting sanctuary from the British. Many Sioux had been allies of the Crown in the War of 1812, and, in the years since, some of them had moved northward in order to escape oppression in the United States.
The American frontier battle at Little Bighorn, Montana, between the U.S. cavalry and the Dakota had serious repercussions for both Canadian Native peoples and the Canadian government. The battle led to the exodus of Sitting Bull and the Hunkpapa people from their homelands on the Bighorn and Powder rivers to the Cypress Hills in Saskatchewan. The bison were fast declining on the Canadian prairies, and the appearance of the bison-hunting Dakota population strained already scarce resources. The N-WMP were particularly concerned about the possibility of a military alliance between the Dakota and the Blackfoot peoples, as Sitting Bull made repeated requests for reserves for his people in Canada. The Canadian government, knowing that the N-WMP could hardly turn back an incursion of U.S. troops into Canadian territory, feared reprisals by American military forces outraged by the annihilation of the Seventh Cavalry at the Battle of the Little Bighorn. The American government pressed Canada to force the Dakota refugees to return to their reserves in South Dakota. Although Canadian officials did not require the Dakota to leave, the N-WMP entreated them to do so on a number of occasions. Eventually, Sitting Bull and many of his followers were forced by imminent starvation to turn themselves in to American authorities. Some 500 Dakota remained in Canada, however, and, though no treaty was ever concluded with them, reserves in Saskatchewan and Manitoba were established, and the Dakota became entitled to Registered Indian status and benefits. Many joined existing Dakota settlements in Saskatchewan and Manitoba that had been formed in the 1860s by refugees from the Minnesota wars.