text: Some accounts repeat a story that an Indian sneaked aboard the St. Peter and stole a blanket from an infected passenger, thus starting the epidemic. The many variations of this account have been criticized by both historians and contemporaries as fiction, a fabrication intended to assuage the guilt of white settlers for displacing the Indians. "The blanket affair was created afterward and is not to be credited", notes B. A. Mann. Given trade and travel patterns, there were numerous ways for people to have been infected, as they had been in earlier, also severe, epidemics.
  Late-19th and 20th centuries
  The Mandan were a party in the Fort Laramie Treaty of 1851. They shared a mutual treaty area north of Heart River with the Hidatsa and the Arikara.
  Soon attacks on hunting parties by Lakota and other Sioux made it difficult for the Mandan to be safe in the treaty area. The tribes called for the United States Army to intervene, and they would routinely ask for such aid until the end of Lakota primacy. Despite the treaty, the Mandan received little protection from US forces.
  In the summer of 1862, the Arikara joined the Mandan and Hidatsa in Like-a-Fishhook Village on the upper Missouri. All three tribes were forced to live outside their treaty area south of the Missouri by the frequent raiding of Lakota and other Sioux. Before the end of 1862, some Sioux Indians set fire to part of a Like-a-Fishhook Village.