Crow Creek massacre
1400 CE.
Shown on the map at 43.980°, -99.332°.
The Crow Creek massacre occurred around the mid-14th century AD and involved Native American groups at a site along the upper Missouri River in the South Dakota area that is now within the Crow Creek Indian Reservation. Crow Creek Site, the site of the massacre near Chamberlain, is an archaeological site and a U.S. National Historic Landmark, located at coordinates 43°58′48″N 99°19′54″W. An excavation of part of the site was done in the 1950s, at the time of dam construction on the river. Additional excavations were conducted in 1978 and later. Two groups occupied the site in prehistoric times. The Siouan-speaking Middle Missouri people (Initial Middle Missouri variant), ancestral to the present-day Mandan people, first occupied the site sometime after about 900 AD. They built numerous earth lodges on the lower portion of the site. Caddoan-speaking Central Plains people (Initial Coalescent variant) moved into the area from southern areas (present-day Nebraska) sometime around 1150 AD. (The present-day Arikara are a Caddoan people.) Whether they displaced the earlier group or moved on to an abandoned site is unknown.
Text from the Wikipedia article Crow Creek massacre, licensed CC BY-SA 4.0.