At least 3,000 years ago the Arapahos, possibly united with the future Gros Ventres and other peoples, probably lived in the western Great Lakes region, where they grew corn and lived in permanent villages. They migrated by the eighteenth century to the upper Missouri River region, acquiring horses about that time.
Medicine bundles, containing various sacred objects, were said by the people to have magical powers. Medicine men (shamans or priests) used their bundles in ceremonies; other bundles belonged to secret societies or to the whole tribe. A flat pipe some two feet long, wrapped in a bundle, was the most sacred object for the tribe. Tobacco was smoked in it only as part of the most sacred ceremonies and occasions.
Each of four bands had a chief, but there was no principal chief. Bands wintered separately, along streams, and came together in the summer to hunt buffalo and celebrate ceremonies. Although menstruating women were avoided, and the subject was taboo, there was no formal girls' puberty ceremony or menstrual seclusion. Men could marry more than one woman. Marriage was generally matrilocal. Blood relative and in-law taboos were strict. Extended family members, such as uncles and aunts, had specific responsibilities concerning their nieces and nephews.
Arapahos played the hoop-and-pole game and the cup-and-ball game and held athletic contests. Curing techniques included sweating in the sweat lodge and fumigation with roots, twigs, or herbs. There was one women's society in addition to the men's societies. The dead lay in state in fine clothing before being removed by horse and buried in a nearby hill. A favorite horse was killed. Mourners cut their hair, wore old clothes, and cut their arms and legs.
Buffalo had become a staple by the nineteenth century. Women made buffalo skin teepees. Willow-framed beds covered with skins lined the interior walls. There were no permanent villages, because the tribe migrated with the buffalo herds. Men also hunted elk, antelope, deer, and small animals. Meat was boiled in a hole in the ground filled with water and hot rocks. To preserve it for the winter, women dried it and sometimes mixed it with fat and chokecherries to make pemmican. They also gathered wild mountain fruits, roots, berries, and tobacco.
Arapahos may once have made ceramics. Most raw materials came from the buffalo or other animals. They carved items such as bowls from wood, some of which had artistic and/or religious significance. They smoked black stone pipes and made shallow basketry trays. Mandan villages along the Knife River (North Dakota) were a primary regional trading center. By the early nineteenth century the Arapaho traded buffalo robes with Mexicans and Americans for items not provided by the buffalo. They also served as intermediaries in trade between northern and southern Plains Indians.
Women decorated clothing, teepees, and other items with beautiful porcupine quill embroidery and painting. Designs often included legends and spiritual beings. Designs, which often represented natural and celestial features, included diamonds with appendages such as forked trees (triangles atop a line). The Arapahos probably acquired horses in the early eighteenth century. Babies were carried on the back in a U-shaped, wood-framed buckskin cradle board. The people used oval snowshoes in the winter.
Eight military societies were graded according to age. One, the Crazy Dog Society, was noted for its extreme bravery and valor. Traditional enemies included the Shoshones, Utes, Pawnees, Crows, Lakotas, Comanches, and Kiowas. The latter three tribes had become allies, with the southern Cheyennes, by the 1840s. Counting coup, or touching, the enemy with the hand or a stick, was highly prestigious, much more so than killing an enemy. Up to four people could count coup, in descending order of prestige, on the same enemy.
In the nineteenth century, the groups separated and divided into northern and southern Arapahos. The northern branch settled around the North Platte River in Wyoming and the southern branch in the area of Bent's Fort on the Arkansas River in Colorado. The two groups remained in close contact. By this time, the Arapahos had adopted the classic Great Plains culture: They were master horse riders, buffalo hunters, and raiders.
Early Anglo traders found the Arapahos very friendly and disposed to trade. Although fur traders entered the area in the 1730s, they merely observed intertribal trade of items of European manufacture, especially knives and guns but also metal tools and other items. Furs were not an important trade commodity until around the turn of the century. Traders also brought alcohol and disease into the region, both to devastating effect. Still, powerful chiefs like Bear Tooth, favorably disposed to non-Indians, kept the peace in the early nineteenth century.
In 1837 a major war broke out, with the southern Arapahos and southern Cheyennes fighting against the Comanches. Peace was established in 1840, largely on Arapaho–Cheyenne terms. However, the opening of the Oregon Trail brought more non-Indians to the Plains and encouraged growing conflict, based on ignorance of Indian customs, land hunger, and race hatred.
Arapahos played a major role in the nineteenth-century wars for the Plains. The northern branch fought along with the Lakotas and the southern branch with the southern Cheyennes and occasionally with the Comanches and Kiowas. Although Arapahos signed the 1851 Fort Laramie Treaty, major gold finds in 1858–1859 caused further friction between Indians and non-Natives. Despite the existence of the treaty, in 1864 a group of southern Arapahos and Cheyennes, mostly women and children, were attacked, massacred, and mutilated by U.S. Army troops at Sand Creek, Colorado, as part of a successful campaign to drive all Indians out of Colorado. Cut off from the rich Colorado buffalo herds and under further pressure from the United States, the Cheyennes and Arapahos in 1867 signed the Medicine Lodge Treaty, under which they formally ceded their lands north of the Arkansas River and were placed on a reservation in the Indian Territory (Oklahoma). Little Raven, a skilled orator and diplomat, represented his people in these negotiations.
By the terms of the Fort Laramie Treaty (1868), the northern Arapahos were supposed to settle with the Lakotas on the Pine Ridge Reservation in South Dakota. Holding out for their own reservation, the northern Arapahos remained in Wyoming, refusing also to settle with the southern Arapahos in the Indian Territory. They finally agreed in 1878 to become part of the eastern Shoshones' Wind River Reservation.
In the eighteenth century, the annual Sun Dance became the most important single ceremony. Its purpose was the renewal of nature and tribal prosperity. Some Arapahos adopted the Peyote religion in the 1890s. Many Arapahos, especially those on the Wind River Reservation, adopted the Ghost Dance religion in the late 1880s. By this time the enormous buffalo herds had been virtually wiped out. In 1890, the Arapahos and southern Cheyennes agreed to exchange their 3.5-million-acre reservation for allotments of 160 acres each. The group formally organized in 1937 as the Cheyenne–Arapaho Tribe.