 Peace with the United States dated back to an alliance arranged by Lewis and Clark, but the encroachment of gold miners in the 1860s and settlers in the 1870s put pressure on the Nez Perce.Although a treaty of 1855 originally allowed them to keep most of their traditional land, another in 1863 reduced the land allotted to them by 90 percent.The Nez Perce who refused to give up their land under the 1863 treaty included a band living in the Wallowa Valley of Oregon, led by Heinmot Tooyalakekt, widely known as Chief Joseph.