The Cheyenne begin to acquire horses and move westward across the Missouri River to the Black Hills.

Trade relationships change as bands of Cheyenne break away. The Northern Cheyenne trade on the Missouri River and the North Platte River with Fort William, later called Fort Laramie. The Southern Cheyenne trade on the Arkansas River with Fort Bent.

The Fort Laramie Treaty of 1851 sets territories for the tribes in the region and establishes two separate territories for the Cheyenne and their Arapaho allies.

Colonel John Chivington and seven hundred Colorado volunteers attack a peaceful camp at Sand Creek and kill almost two hundred Cheyenne and Arapaho people.

The Southern Cheyenne and Arapaho sign the Treaty of Little Arkansas. The U.S. government admits guilt for the Sand Creek Massacre.

The Southern Cheyenne and Arapaho sign the Medicine Lodge Treaty, which establishes a reservation bound by the 37th parallel and the Cimarron and Arkansas Rivers. According to official interpreter George Bent, the treaty “marked the beginning of the end of the Cheyenne as free and independent warrior and hunter.”

Lieutenant Colonel George Custer leads an early-morning attack on Peace Chief Black Kettle’s camp at Washita. The army burns the village, destroys supplies and livestock, kills the men, and captures the women and children. Black Kettle and his wife are among those killed.

Lieutenant Colonel George Custer smokes the sacred pipe with Stone Forehead, Keeper of the Sacred Arrows.

General Eugene Carr’s troops and Pawnee scouts attack Tall Bull’s Dog Soldier village at Summit Springs, Colorado. Tall Bull, a Cheyenne chief, and fifty-one others are killed. According to American interpreter George Bent, this is the last great fight of the Cheyenne Dog Soldiers.

Colonel Ronald Mackenzie and his troops attack five camps of Southern Cheyenne, Kiowa, Comanche, and other Indians in Palo Duro Canyon, Texas. They destroy more than one hundred lodges and all of the Indians’ supplies.

Several Southern Cheyenne including Howling Wolf and Black Horse are sent to prison at Fort Marion in St. Augustine, Florida, for their part in uprisings in Indian Territory and Texas.

The combined forces of Sioux, Northern Cheyenne, and Arapaho Indians defeat General George Custer and the 7th Cavalry at the present-day Little Bighorn Battlefield, Montana.

President Rutherford Hayes meets with a delegation of Arapaho and Sioux Indians in the East Room of the White House. Arapaho Chief Sharp Nose gives President Hayes a pipe and tobacco pouch.

More than three hundred Northern Cheyenne escape from the Cheyenne and Arapaho Agency at Fort Reno, Oklahoma, to return to their home in the north. They are led by Chiefs Dull Knife and Little Wolf and guided by an elderly woman.

General Phillip Sheridan and Secretary of the Interior Carl Schurz order Chief Dull Knife and his Cheyenne to leave Fort Robinson, Nebraska, and return to their reservation in Indian Territory. But the Indians make a daring nighttime escape.

The Northern Cheyenne reservation is established by executive order on the Tongue River Agency, Montana.

The Dawes Severalty Act is passed, which allots tribal reservation land to individual Indian owners and makes surplus land available for sale. Indians willing to give up their culture and live like white men are granted American citizenship.

The Oklahoma Organic Act establishes the Oklahoma Territory from unassigned lands and the neutral strip of territory known as the “panhandle.”

Tribal lands are divided into 160-acre tracts and assigned to individual Cheyennes. Unassigned or surplus land is made available to white settlers.

The United States Congress grants citizenship to all American Indians.

The Indian Reorganization Act is passed to secure rights for Native Americans on reservations by restoring self-management of their assets (mostly land) and local self-government on a tribal basis.

Cheyenne-Arapaho Tribes of Oklahoma ratify their tribal government constitution and bylaws.

Cheyenne-Arapaho Tribes of Oklahoma ratify a revised constitution and bylaws.

Ben Nighthorse Campbell, a Northern Cheyenne Indian and one of the forty-four Northern Cheyenne chiefs, is elected to the U.S. House of Representatives. In 1992, he is elected to the Senate.

Cheyenne repatriate the remains of victims of the Sand Creek Massacre from the Smithsonian Institution.

Sand Creek Massacre National Historic Site is authorized by Public Law No. 106-465.

The Sand Creek Massacre site is approved for the National Registrar of Historic Places.

Gordon Yellowman Sr. is honored in the East Room of the White House.

The National Museum of the American Indian opens on the National Mall in Washington, D.C. Museum director and Southern Cheyenne Peace Chief W. Richard West Jr. says, "Once in a great while, something so important and so powerful occurs that, just for a moment, history seems to stand still––and silent––in honor. I sense that this place and this time in the fall equinox season of 2004 is one of those moments."