Along in 1871 the Northern Pacific Railroad wished to build westward. The route would take them through the country given to the Sioux, and the Sioux said no. Their treaty protected them against the white man's roads. They attacked a surveying party escorted by soldiers, and killed two. This was in 1872.
It was a brutal killing. Rain-in-the-face was arrested for this, on the reservation; but he escaped and vowed vengeance. He went to Sitting Bull, and was safe.
In 1874 the United States began to ask for the Pah-sap-pa, or Black Hills, in South Dakota. To the Sioux and the Cheyennes, Pah-sap-pa was medicine ground. Spirits dwelt there; it was the home of the Thunder Bird and other magic creatures; it contained much game, and quantities of tent poles, for lodges.
Spotted Tail of the Brulés went in. He hung around the white men's mining camps, and found out that the white men were crazy for the gold.
The United States had been accustomed to buying Indian land cheap, and getting rich out of it. Now it offered to buy the Black Hills for six millions of dollars, or to rent them for four hundred thousand dollars a year.
Coached by Spotted Tail and by Red Cloud, the Sioux laughed, and asked sixty millions of dollars. So the deal did not go through, this time. However, the Sioux lost Pah-sap-pa, just the same.
The United States Government was unable to keep the gold-seekers out. They dodged through the troops. There were fights with the Sioux, and the Sioux became angered in earnest.
They saw their Black Hills invaded by a thousand white men. Other white men, guarded by soldiers, were planning to run a railroad right through the Powder River country. On the Great Sioux reservation Spotted Tail and Red Cloud were the head chiefs; but out on the hunting grounds the Sitting Bull people stayed and prepared to make war and hold the Sioux lands.
The Sioux on the reservations began to leave, and join Sitting Bull. They felt that Red Cloud's heart was with them. He had notified the United States that it must keep the white men out of Sioux country.
The United States also was alarmed. The Sioux seemed to be using the reservation as a sort of supply depot; they got provisions and clothing there, and took them to the hunting grounds.