The treaty period intensified the intratribal estrangement between the Christian and more sedentary Nez Perce bands, mostly situated along the Clearwater River, and the non-Christian bands who continued to occupy remote locations in west-central Idaho and to partake of the seasonal hunting migrations east of the Bitterroots. A principal group of the latter, the Wallowas, inhabited the area west of Snake River and east of the Wallowa Valley of present northeastern Oregon. They perennially camped there and in the nearby Imnaha Valley, beautiful well-watered grassy pockets beneath the Wallowa range. Known for its grazing potential, the area afforded a popular summer rendezvous for other Nez Perce bands and for various Cayuse bands as well. Another prominent non-Christian group, the Lamtamas, inhabited the Salmon River tributaries, including White Bird Canyon, at the western edge of the Clearwater Mountains and southeast of Camas Prairie. The Alpowai band traversed the entire Nez Perce domain, but generally ranged along the upper middle Clearwater and spent much time east of the Bitterroots, often camping along the Yellowstone River. Yet another traditional group was the Pikunans, who occupied the region between the Snake and Salmon rivers. Finally, the closely related Sahaptian-speaking Palouses lived in several villages north of the big bend of the Snake, near its junction with the Columbia. 
By the mid-1850s, as the treaty period began, several leaders representing the various Nez Perce bands reflected the growing factionalism in the tribe. One Indian, Hallalhotsoot (Shadow of the Mountain), known appreciatively as Lawyer among whites, had strongly influenced the establishment of a Presbyterian mission at Lapwai near the lower Clearwater. Because of Lawyer's affinity for the Christian religion and his endorsement of missionary activities, church leaders and federal authorities recognized him as nominal head of all the Nez Perces. Other Nez Perce leaders who played significant roles at the outset of the reservation period included the great war leader Apash Wyakaikt, or Looking Glass, a rival of Lawyer for the position of head chief; Tuekakas, known as Old Joseph, of the Wallowa band, who had converted to Christianity in 1839; Timothy, of the Alpowai; and James, or Big Thunder, from Lapwai Valley. 
Among these men, Old Joseph played a most significant part in the coming crisis of 1877. When the missionaries had arrived among the Nez Perces, Spalding baptized him a Christian, and the chief moved his people from Wallowa to Lapwai. As a reputable warrior and hunter, Old Joseph had gained enviable status as a leader, and his presence at the mission, where Spalding openly favored him, deprived the local chief, James, of influence and created resentment. After the mission closed in 1847, Joseph returned to Wallowa but continued his Christian ways. He would factor importantly in the imminent developments that created, then modified, the Nez Perce reservation, and he spoke strongly for retaining his people's Wallowa lands: "There is where I live and there is where I want to leave my body." But undeniably, Old Joseph's most important contribution lay in his progeny, as the course of events would prove. 
As the intrusion of whites into the Northwest proceeded, the U.S. government took steps to acquire coveted lands and to avoid conflict with the native inhabitants by concentrating them on specially reserved tracts. Through the treaty process, the government extinguished the Indians' right of occupancy to selected areas. In 1855, Washington territorial governor Isaac I. Stevens engineered such agreements with several area tribes, including the Yakimas, Umatillas, Walla Wallas, and Cayuses. The first treaty with the Nez Perces was concluded on June 11, 1855, near Fort Walla Walla, Washington Territory, with Lawyer, Looking Glass, and Old Joseph prominent among the fifty-eight Nez Perces who signed it. The document recognized much of the generally acknowledged geographical perimeter of the ancestral Nez Perce domain, creating a reservation of about five thousand square miles that stretched from the Blue Mountains and upper Grande Ronde River of Oregon Territory, east to embrace the Clearwater Mountains all the way to the Continental Divide, and south from the Palouse River to include the lands between the Snake and Salmon. By the treaty, to which only Old Joseph and Looking Glass among the so-called lower bands acquiesced, the Nez Percesin return for specified money, goods, and servicesceded to the United States lands on the east running into the Bitterroots, and on the south lands lying far below the junction of the Salmon with the Snake. 
For many signatory tribes who gradually realized the enormity of their losses by treaty, war seemed the only recourse. Within months of the council, war with the Yakimas erupted, followed by prolonged conflict with the Spokans, Walla Wallas, Cayuses, and Palouses. Thirty-nine Nez Perce tribesmen garbed in U.S. uniforms accompanied federal troops in several of the operations. Significantly, but perhaps not surprisingly, the 1855 treaty immediately caused no major disruption among the Nez Perces because the reservation encompassed much of the traditional band homelands, and notably that of the Wallowas west of the Snake River. But the instrument's inherent failure to recognize a multiple-band tribal composition and its acknowledgment of a head chief concept helped aggravate political divisiveness among the Nez Perces in ensuing years. Besides the alien nature of the transaction, many Nez Perces failed to consider Lawyer a chief. He therefore lacked legitimacy to deal with the whites, and to those bands, his signing the treaty invalidated it. 
At a council convened in September 1856, Old Joseph and other of the lower Nez Perce band leaders attempted to clarify their perceptions of the treaty and to explain that their accedence was in no way meant to constitute surrender of their lands. The "Nez Perces are divided in their loyalty," Governor Stevens reported, "one half of them . . . being in favor of, and one half against the treaty."  Equally disturbing to Nez Perce adherents of the treaty of 1855 was the failure of Congress to ratify it for nearly four years, a delay that nonetheless witnessed the opening of the Nez Perce cession lands to settlement. Too, even after ratification, the government equivocated over providing the goods promised in the agreement. As Lawyer pointed out nine years later, "we have no church as promised; no school house as promised; no doctor as promised." The government's delinquency was not lost on the Nez Perces who had refused to participate in the pact and who took every opportunity to remind Lawyer's followers of their folly. Compounding all, rich gold discoveries in the Nez Perce country during the summer and autumn of 1860 soon produced an influx of nearly fifteen thousand miners, directly contravening the 1855 treaty. In addition, in 1861 an agreement with the Nez Perces (not confirmed by Congress) permitted opening of a portion of the reservation "to whites in common with the Indians for mining purposes." From staging areas at Walla Walla, Washington Territory, and the newly founded Lewiston, on the Snake opposite the mouth of the Clearwater and itself on the reservation, the miners advanced onto Nez Perce lands without regard for treaty stipulations. In eastern Oregon, too, the Blue Mountains attracted gold seekers. Everywhere their impacts on the Nee-Me-Poo multiplied as boomtowns alternately were founded, flourished, and died along the Salmon and Clearwater and their tributaries. With placer deposits yielding upwards of five million dollars per annum during the early years of the strike, federal officials believed the gold country should remain open. 
The invasion by prospectors produced the greatest trauma that the Nez Perces had known in the long span of their relations with whites. Although the peopleChristian and non-Christian alikereaped rewards from the sale of pack horses and cattle to whites entering their lands, they ironically acquired through their transactions a dependency encouraged by ready access to white men's goods, such as firearms, food, and hardware. As roads and trails quickly traced through the country, the miners increasingly subjected the people to all forms of abuse. Whiskey sales and consumption occurred with uncontrolled frequency near the Nez Perce villages, while miners often destroyed or confiscated the tribesmen's property, including buildings and fences. In an attempt to preserve order, the army established Fort Lapwai near the new Indian agency of that name located near Spalding's vacated mission, but the presence of troops had little effect. By late 1862, the Nez Perces, in addition, faced loss of their grazing lands to the covetous intruders, a circumstance that prompted the government to act. In 1863, in an attempt to prevent hostilities, to open the gold country, and ostensibly to protect the Nez Perces from further aggression by whites, commissioners arrived at Fort Lapwai, in the new Territory of Idaho, to negotiate a treaty that would relinquish to the United States a major part of the reservation. 
The resulting treaty of 1863 not only removed the extensive land base accorded the Nez Perces eight years earlier, it exacerbated the long-standing political and religious divisions simmering among the tribesmen. Although the largely non-Christian bands attended the deliberations, they steadfastly refused to participate with the bands headed by Lawyer. The treaty, by relinquishing all lands part of Washington Territory and the state of Oregon, drastically reduced the reservation to approximately one-tenth of its 1855 size. The redefined boundaries, dictated largely by the location of gold fields and their supporting communities, created a tract bordering both sides of Lapwai Creek and the middle and south forks of the Clearwater River, but continuing south through the Camas Prairie to some of the northern affluents of the Salmon. 
Most important, however, the redesignated area (784,996 acres) coincidentally encompassed only the lands of the Christianized Nez Percesabout three-fourths of all the tribesmenwhose government-supported leaders readily acceded to the treaty, while excluding those of the isolated Nez Perce bands from the Wallowa and Salmon River regions, whom it nonetheless directed to move onto the new reservation within one year of ratification. By their omission from the newly prescribed boundary, those people lost legal recognition altogether in the Treaty of 1863; in turn, they never recognized the accord. Old Joseph openly renounced his conversion to Christianity. By reaffirming nontraditional forms of government and leadership, the treaty further aggravated fragile intratribal relations, causing the remote lower bands to more completely reject acculturation and to more firmly embrace the Dreamer faith. But the compact engendered anti-white feelings and created certain sympathy among the treaty people, too, and some defections to the nontreaty bands occurred after promised annuities again failed to appear (the treaty was not ratified until 1867). Thereafter, the reservation faction of the Nez Perces, thus endorsed by the government, would benefit not only economically, but militarily, if such support were needed. 
Because the Wallowa lands had, in effect, been yielded by the pro-government majority represented by Lawyer's people, the action was repudiated by the lower bands headed by Old Joseph, Looking Glass (son of the chief of the same name, who had died early in 1863), White Bird, Big Thunder, Eagle From the Light, Toohoolhoolzote (Sound), and others, and Nez Perce occupation continued there under tacit consent of the U.S. government. But the Wallowa band and its allies remained off the reservation, and after the death of Old Joseph in 1871, the issue came to crisis with accelerated movement into the Wallowa Valley by white settlers. A commission met with Old Joseph's son, Heinmot Tooyalakekt (Thunder Traveling to Loftier Mountain Heights), known to whites as Young Joseph, and reported favorably that the valley had been permanently reserved for Joseph's people in 1855 and that they had not subscribed to any provisions of the 1863 accord. Furthermore, the commissioners concluded that the pro-treaty Nez Perces had lacked authority to relinquish the Wallowa lands, adding that "if any respect is to be paid to the laws and customs of the Indians, then the treaty of 1863 is not binding upon Joseph and his band, [and] . . . the Wallowa valley is still a part of the Nez Perce reservation." A caveat declared, however, that either the white settlers or the Indians must ultimately leave the area to insure mutual safety. 
The secretary of the interior, charged with administering Indian affairs through the Bureau of Indian Affairs, concurred with the commission's report, recommending nonetheless that a designated part of the Wallowa be retained for white settlement. At his behest, President Ulysses S. Grant issued an executive order, June 16, 1873, prescribing that parts of the Wallowa and Imnaha lands "be withheld from entry and settlement as public lands, and . . . be set apart as a reservation for the roaming Nez Perce Indians."  The decision to recognize the nontreaties' claim was strangely incongruous, given the government's post-Civil War trend toward restricting the tribes to reservations while opening more lands to white emigrants. Settlers already occupying specific areas of the Wallowa Valley and expected now to leave that place would be indemnified by congressional appropriation. Lapwai Agent John B. Monteith, Presbyterian appointee of the Grant administration under its church-oriented "Peace Policy," notified Chief Joseph of the government's recognition of the nontreaty Nez Perces' claim to the Wallowa.
Yet the presidential order failed either to evict whites already settled on the Wallowa lands or to prevent inroads there by many more. Both treaty and nontreaty Nez Perces continued to use the Wallowa for grazing stock during the winter months; they then generally moved east to cooler elevations each summer. Most whites arrived and established their farms in the summer while the tribesmen were away, then challenged the occupancy of the returning tribesmen.  Hoping to prevent clashes, Agent Monteith called on the tribesmen to come on the reservation and protect themselves against the crowding of settlers. Advocating their acculturation, he further urged that the Nez Perces stop going to the buffalo country. "When they go they stay one year, consequently nothing can be done toward civilizing such, and by their example they keep others from settling down." Monteith especially disliked the fact that the nontreaty returnees fraternized yearly with many of his charges along the Clearwater. 
Another source of contention that had developed concerned the frequency of Nez Perce murders at the hands of white men. As many as twenty-five tribesmen had been slain in the interval since the onset of the gold rush, and justice had been meted out badly or not at all. A singular case that profoundly affected the course of events three years later was the shooting death of Tipyahlana Siskan (Eagle Robe), a nontreaty Indian, by a settler named Lawrence Ott in the spring of 1874 on the Salmon River. The dispute between the two evolved over land, and although Ott turned himself in, he went unpunished for the crime. 
The Ott affair signaled the growing frustration that the Nez Perces felt regarding their relations with the whites vis-à-vis their lands. Finally, Oregon officials demanded all Nez Perce claims to land within the state boundary be extinguished.  Bowing to political pressure, on June 10, 1875, President Grant revoked his executive order, thereby restoring the Wallowa tract to the public domain and reopening it for settlement.  The fact that Joseph's people occupied the Wallowa but intermittently in their seasonal peregrinations, showing "no inclination to make permanent settlement thereon," was claimed to justify the action, which paved the way for unrestricted intrusions and consequently provoked conflict with the nontreaty Nez Perces.  While Joseph counseled restraint, often moving his people to avoid confrontation, conflicts with the homesteaders erupted. A catalytic event was the malicious killing of a Wallowa tribesman by two white men in June 1876, an outrage that, while duly acknowledged, was not promptly mitigated by the authorities.