As the Pacific-bound wagon trains rumbled across Nebraska along the broad Platte River, the migrants encountered the unique ecology of the Great Plains. A vast sea of wild grasses stretched from Texas to Saskatchewan in Canada, and west from the Missouri River to the Rocky Mountains. Tall grasses flourished in the eastern regions of the future states of Kansas, Nebraska, and the Dakotas, where there was ample rainfall. To the west, in the semiarid region beyond the 100th meridian, the migrants found short grasses that sustained a rich wildlife dominated by buffalo and grazing antelopes. Nomadic buffalo-hunting Indian peoples roamed the western plains, while the eastern river valleys were home to semisedentary tribes and, since the 1830s, the Indian peoples whom Andrew Jackson had “removed” to the west. A line of military forts — stretching from Fort Jesup in Louisiana to Fort Snelling, then in the Wisconsin Territory — policed the boundary between white settlements and what Congress in 1834 designated as Permanent Indian Territory.

For centuries, the Indians who lived on the eastern edge of the plains, such as the Pawnees and the Mandans on the Upper Missouri River, subsisted primarily on corn and beans, supplemented by buffalo meat. They hunted buffalo on foot, driving them over cliffs or into canyons for the kill. To the south, the nomadic Apaches acquired horses from Spanish settlers in New Mexico and ranged widely across the plains. The Comanches, who migrated down the Arkansas River from the Rocky Mountains around 1750, developed both a horse-based culture and imperial ambitions. Skilled buffalo hunters and fierce warriors, the Comanches slowly pushed the Apaches to the southern edge of the plains. They also raided Spanish settlements in New Mexico, incorporating captured women and children into their society.

After 1800, the Comanches gradually built up a pastoral economy, raising horses and mules and selling them to northern Indian peoples and to Euro-American farmers in Missouri and Arkansas. Many Comanche families owned thirty to thirty-five horses or mules, far more than the five or six required for hunting buffalo and fighting neighboring peoples. The Comanches also exchanged goods with merchants and travelers along the Santa Fe Trail, which cut through their territory as it connected Missouri and New Mexico. By the early 1840s, goods worth nearly $1 million moved along the trail each year.

By the 1830s, the Kiowas, Cheyennes, and Arapahos had also adopted this horse culture and, allied with the Comanches, dominated the plains between the Arkansas and Red rivers. The new culture brought sharper social divisions. Some Kiowa men owned hundreds of horses and had several “chore wives” and captive children who worked for them. Poor men, who owned only a few horses, had difficulty finding marriage partners and often had to work for their wealthy kinsmen.

While European horses made Plains Indians wealthier and more mobile, European diseases and guns thinned their ranks. A devastating smallpox epidemic spread northward from New Spain in 1779–1781 and killed half of the Plains peoples. Twenty years later, another smallpox outbreak left dozens of deserted villages along the Missouri River. Smallpox struck the northern plains again from 1837 to 1840, killing half of the Assiniboines and Blackfeet and nearly a third of the Crows, Pawnees, and Cheyennes. “If I could see this thing, if I knew where it came from, I would go there and fight it,” exclaimed a distressed Cheyenne warrior.

European weapons also altered the geography of native peoples. Around 1750, the Crees and Assiniboines, who lived on the far northern plains, acquired guns by trading wolf pelts and beaver skins to the British-run Hudson’s Bay Company. Once armed, they drove the Blackfoot peoples westward into the Rocky Mountains and took control of the Saskatchewan and Upper Missouri River basins. When the Blackfeet obtained guns and horses around 1800, they emerged from the mountains and pushed the Shoshones and Crows to the south. Because horses could not easily find winter forage in the snow-filled plains north of the Platte River, Blackfoot families kept only five to ten horses and remained hunters rather than pastoralists.

The powerful Lakota Sioux, who acquired guns and ammunition from French, Spanish, and American traders along the Missouri River, also remained buffalo hunters. A nomadic war-prone people who lived in small groups, the Lakotas largely avoided major epidemics. They kept some sedentary peoples, such as the Arikaras, in subjection and raided others for their crops and horses. By the 1830s, the Lakotas were the dominant tribe on the central as well as the northern plains. “Those lands once belonged to the Kiowas and the Crows,” boasted the Oglala Sioux chief Black Hawk, “but we whipped those nations out of them, and in this we did what the white men do when they want the lands of the Indians.”

The Sioux’s prosperity also came at the expense of the buffalo, which provided them with a diet rich in protein and with hides and robes to sell. The number of hides and robes shipped down the Missouri River each year by the American Fur Company and the Missouri Fur Company increased from 3,000 in the 1820s, to 45,000 in the 1830s, and to 90,000 annually after 1840. North of the Missouri, the story was much the same. The 24,000 Indians of that region — Blackfeet, Crees, and Assiniboines — annually killed about 160,000 buffalo. The women dried the meat to feed their people and to sell to white traders and soldiers. The women also undertook the arduous work of skinning and tanning the hides, which they fashioned into tepees, buffalo robes, and sleeping covers. Over time, Indian hunters increased the kill and traded surplus hides and robes — about 40,000 annually by the 1840s — for pots, knives, guns, and other Euro-American manufactures. As among the Kiowas, trade increased social divisions. “It is a fine sight,” a traveler noted around 1850, “to see one of those big men among the Blackfeet, who has two or three lodges, five or six wives, twenty or thirty children, fifty to a hundred head of horses; for his trade amounts to upward of $2,000 per year.”

Although the Blackfeet, Kiowas, and Lakotas contributed buffalo hides to the national economy, they did not fully grasp their market value as winter clothes, leather accessories, and industrial drive belts. Consequently, they could not demand the best price. Moreover, the increasing size of the kill diminished the buffalo herds. Between 1820 and 1870, the northern herd shrank from 5 million to less than 2 million. When the Assiniboines’ cultural hero Inkton’mi had taught his people how to kill the buffalo, he told them, “The buffalo will live as long as your people. There will be no end of them until the end of time.” Meant as a perpetual guarantee, by the 1860s Inkton’mi’s words prefigured the end of time — the demise of traditional buffalo hunting and, perhaps, of the Assiniboines as well.