Nimipu is the name by which the Nez Perce call themselves.

Before white settlers came to the area, the Nez Perce territory is estimated to have covered some 28,000 square miles. Many bands lived on the upper Clearwater River, in the Kamiah Valley. Other groups lived near the confluence of the Clearwater and Snake rivers near present-day Lewiston and the Salmon RIver, both in Idaho, as well as in the Wallowa Valley, in northeastern Oregon.

The horse became an integral part of Nez Perce life during the 18th century, giving them greater mobility. On the prairie grasslands of the Nez Perce homeland, their herds multiplied rapidly. In a time when horses equalled wealth, the Nez Perce were known as an affluent tribe.

A tired and starving Lewis and Clark expedition ventured into Nez Perce territory in 1805. The Nez Perce offered them food, helped them build canoes, and guided them down the Clearwater River toward the Snake and Columbia rivers. The Nez Perce kept the expedition's horses until they returned from the Pacific Coast the following May. They were remembered fondly by Lewis and Clark.

A mission was established by Henry and Eliza Spalding in 1836. Although Spalding claimed many converts, his lack of tolerance for Nez Perce culture caused him to alienate large segments of the tribe. It was the beginning of a deep division within the tribe.

In 1855, a treaty was signed that granted the Nez Perce a reservation, which included most of their traditional homelands in its seven million acres.

In 1860, gold was discovered on the Nez Perce Reservation. During the next few years, miners swarmed illegally onto the reservation. The supply town of Lewiston was established on Indian land. All such activity was in clear violation of the 1855 treaty, which made the reservation off-limits to whites.

After the gold rush, the Federal government pressured the Nez Perce into accepting a new treaty in 1863. The treaty reduced the Nez Perce reservation by 90 per cent. Many of the Christian Nez Perce leaders signed the treaty, while more traditional leaders did not. The split between the Christian and non-Christian Nez Perce widened. The two factions became known as Treaty and non-Treaty.