In-mut-too-yah-lat-lat (c.1840–1904), or Thunder Traveling over the Mountains, known in English as Chief Joseph, is remembered as a valiant leader who attempted to preserve the way of life of his people, the Nez Percé, in the face of overwhelming odds. He was born in Wallowa Valley, the ancestral home of the Nez Percé, in what the United States government then called Oregon Territory. His father, a Nez Percé chief, had been converted to Christianity, and Joseph himself attended a school run by missionaries. In the first part of the nineteenth century, relations between the Nez Percé and the persons of European descent in their midst were fairly good. However, relations became strained with increasing white settlement. At that time, the United States government negotiated treaties with some Nez Percé to obtain land rights for the settlers, but the Nez Percé did not consider the negotiators to be their legitimate representatives.

In 1877, Chief Joseph was preparing to move with his people to a reservation in Idaho when he learned of an attack that had been made by three Native Americans on some settlers. Fearing reprisals, Joseph decided to flee with his people to Canada. Pursued by troops of the United States Army, this group of men, women, and children traveled over a thousand miles, often meeting and defeating their pursuers in combat. Surrounded by United States troops and recognizing that his weakened, small band had the means neither to escape nor to continue fighting, Chief Joseph surrendered in October of 1877, only forty miles from the Canadian border and freedom. The Nez Percé under Chief Joseph were further decimated by sickness after their removal to a temporary reservation in what is now Oklahoma. In 1885, those who remained were sent to the Colville Indian Reservation in Washington State.