Today they live primarily on the Colville Indian Reservation in Washington, where they form part of the Confederated Tribes of the Colville Reservation, which is recognized by the United States government as an American Indian Tribe. A few Sinixt live in their traditional West Kootenay territory, particularly the Slocan Valley. They are no longer legally recognized by the Canadian government.
In prehistoric times, the Sinixt were a semi-sedentary people, living in warm, semi-subterranean houses for the winter months. Summers were spent managing fishing, hunting, and other food resources in their mountain and lake-dominated homeland. Reyes says that they wintered in the more wind-sheltered valleys, but summered by the Columbia. Scholars have classified the Sinixt as "complex collectors" (as opposed, for example, to "hunter-gatherers").
Sharon Montgomery of the Nakusp Museum, describes the Sinixt as the "Mother Tribe" of the Pacific Northwest Salish, and, in a recent interview with journalist Rex Weyler, "Headman" of the Sinixt in British Columbia, Bob Campbell notes that "As the mother nation, we often settled disputes among the (other) bands." Both claims, among others made in the article, were refuted as being without ethnographic or historical foundation by contributors to the article's forum.
Early white explorers reported the Sinixt to be of average height and size, with hazel eyes, adept in making suspended bridges over the narrow, swift-flowing Columbia, and skillful at fishing.
Their staples included huckleberry, salmon, and roots (camas, bitterroot), but they also ate black moss, other berries (serviceberry, gooseberry, and foam berry), hazelnuts, wild carrots, peppermint, and various game meats (deer, elk, moose, caribou, rabbit, mountain sheep, mountain goat, and bear; after the coming of the horse, they also ventured east after bison). They chewed pine pitch like gum, and had a range of herbal medicines. Starting in June, mature salmon arrived at Kettle Falls, the farthest their territory extended down the river. The Sinixt approach to fishing caught only the salmon that were not strong enough to clear the falls, ensuring that only the strongest went on to spawn. Both bands traveled to Red Mountain near Rossland, B.C. to harvest huckleberries in August. Both of these events figured prominently in their culture. They hunted in late autumn, but still often were short on food in late winter.
The Upper Sin Aikst trained dogs to drive deer toward the Columbia, where hunters in canoes shot them with bow and arrow. The Sin Aikst used the distinctive Sturgeon-nosed canoe; about 15–17 feet (4.5–5 meters) long with a cedar frame covered by large slabs of pine bark, riding low in the water with downward-sloping tips to reduce wind resistance.
Reyes says that they often intermarried with the Swhy-ayl-puh (Colville), who had a very similar language; the territory of the latter was largely in the Colville Valley and intersected Sinaixt territory at Kettle Falls.
Reyes gives an account of various Sinixt customs, especially related to pregnancy, birth, and education, as well as some descriptions of funerary customs. Children were "closely monitored" by elders. Children were sent on "short excursions" to search for protective spirits; they were usually required to bring back an object to prove that they had actually made the journey. As they grew older, until puberty, these journeys became longer. Each person was expected to acquire multiple spirits, because each had different powers.
At about the age of six, they began to be instructed in "the legends of the tribe and family history…, tribal ways and tribal laws." At eight or nine, they learned to swim and to run long distances; boys were taught to make and use weapons and fishing gear, while girls started to learn plant lore and tanning, as well as how to care for young children, maintain dwellings, and prepare meals.
The whole tribe was led by one head chief (ilmi wm), but each smaller village of 50-200 had a local chief, whom they called a "thinker". These "thinkers" would come together to form a council.
The Sinixt were a Matrilocal people, with next generations choosing to reside with the wife's family rather than the husband's.
The Ktunaxa (Kutenai) people who neighboured the Sinixt to the east were driven further into the mountains by the Blackfoot, who had obtained control of Ktunaxa territory in the foothills and northwestern plains. There is ethnographic and historical evidence suggesting the Ktunaxa and the Sinixt battled each other over the territory along the lower Kootenay River between the present cities of Nelson and Castlegar, British Columbia. The Ktunaxa were considered the intruders, and the dispute was reportedly ended after the Sinixt mounted a large-scale raid into (Lower) Ktunaxa Territory at the South end of Kootenay Lake. The Sinixt later renewed their historic peace with the Ktunaxa, and took common cause with them, the Kalispel, the Flathead, the Coeur d'Alene, the Spokane, the Nez Perce, and others against the Blackfoot. While the Sinixt never directly fought the Blackfoot as a group, it is very likely that individual Sinixt joined their Salishan neighbours (and the Ktunaxa) in war parties and buffalo hunts to the Western Plains. Reyes says they had ongoing skirmishes with the Blackfoot, from whom, according to him, they stole horses. They also took part with other regional peoples in the punitive expedition in 1838 against the St'at'imc of Seton Lake led by Nicola (Hwistesmexteqen), chief of the Nicola people. They also were in the alliance of Interior tribes led by the Nlaka'pamux who assembled at Lytton (Camchin) during the Fraser Canyon War of 1858.
In 1837, Jesuit missionaries arrived in the area. St. Paul's Mission at Kettle Falls was constructed with the help of Colville and Sinixt labor. According to Reyes, it was in the 1840s that the Sinixt experienced a major die-off, shrinking from about 3,000 to about 400 during the period of chief Kin-Ka-Nawha, nephew of See-Whel-Ken. Besides diseases and incursions on their land, the salmon runs began to diminish because to the development of commercial fisheries at Astoria, Oregon near the mouth of the Columbia. Some saw the die-off as a failure of the powers of their traditional religion; Kin-Ka-Nawha was, himself, among the eventual converts to Catholicism.
In the wake of the partition, the Hudson's Bay Company created Fort Shepherd, just upstream from the confluence of the Pend d'Oreille and Columbia Rivers, which was very near the border, in order to serve their former clients and also maintain a post on British territory Adjacent Sinixt territory in British Columbia remained in the hands of the Sinixt. As late as the 1860s, Sinixt leaders still equated British title in their Northern territory as signifying Sinixt sovereignty. When Fort Shepherd was abandoned by the Hudson's Bay Company, for example, it was left in Sinixt hands.
However, their reduced numbers resulted in the Sinixt being unable to control development of the area as it was flooded with miners during a second mineral rush in the 1880s and '90s. Several boomtowns were erected throughout the West Kootenay Region. The majority of Sinixt continued to live in Washington State, among the security of their friends and relatives on the Colville reserve. Nevertheless, a number of Sinixt remained permanently in Canada during the first half of the 20th century. Many others also returned to their ancestral land in B.C. to hunt and fish during the summer months well into the 20th Century.
Kin-Ka-Nawha resigned his role as chief as an old man. He was succeeded by Joseph Cotolegu, with Aorpaghan and James Bernard (c. 1870–1935) as subchiefs. They would succeed him, in turn, as leaders.
Initially, the Confederated Tribes were given a reservation east of the Columbia. Three months later, it was taken away (because white settlers wanted it) and they were given a comparably large tract on the west side of the river on inferior land. Initially this reservation extended all the way to the Canadian Border, but the northern half was taken away in 1892, which separated it from Sinixt traditional territory in British Columbia; in addition, as more tribes lost their land, the shrinking reservation had to absorb yet more people. Even then, they had to deal with incursions of miners, homesteaders, and settlers such as the Doukhobors, who arrived from Russia in 1912.
In 1900, Aropaghan, over James Bernard's objection, agreed to have the land divided into individual allotments rather than held in common; he also agreed to include "half breeds" equally in the allocation.
Bernard journeyed three times to Washington, D.C. on behalf of his people: first in 1890 as interpreter for Chief Smitkin of the Colvilles, then in 1900 with Chief Lot and Chief Barnaby to negotiate the reservation boundaries, and finally in 1921 as chair of a delegation of the Confederated Tribes.
A permanent Sinixt presence was reestablished in British Columbia during the late 1980s when, following direction by an elder, a number of Sinixt descendents returned to the Slocan Valley to protest road building affecting an important village site, now called the Vallican Heritage Site. A bridge being built at Vallican resulted in a road being placed very near the large pithouse village and ancient burial site. Since 1989, a permanent Sinixt presence continues in the Slocan Valley, with local members overseeing the repatriation of remains and playing an increasing role in local affairs.
There were more than 250 Sinixt in Washington State at the time the Canadian Government declared the Sinixt extinct, along with other self-identifying Sinixt who had relocated with relatives to the Canadian part of the Okanagan region.
Similar to the conflicting Ktunaxa land claims territorial claims shown on maps published by the Okanagan Nation Alliance, of which the Colville Tribes is the American-side member, do not show Sinixt territory and rather show the region as part of Okanagan traditional territory.
On July 28, 2008, "directors of the Sinixt Nation Society have filed a lawsuit claiming aboriginal title to Crown land in the Kootenays. Their lawyer David Aaron describes the intent of the action as "asserting a right (for the Sinixt) to be consulted, and to consent to all uses or dispositions of Crown land within that territory," and notes that private lands in the area will not be affected by the claim.
Several Sinixt in the group's northern territory host a weekly radio program, Sinixt Radio, on Nelson, B.C. Community Radio station CJLY-FM. The northern Sinixt also host an annual Barter Fair every September in Vallican, B.C. The event features live music and performance, and it is set up to encourage local Bartering of goods and services.
Novelist and memoirist Mourning Dove (author), also know as Christine Quintasket, is described by anthropologist Paula Pryce as of Sinixt-Skoyelpi descent, and Quintasket describes her childhood and youth at Pia (now Kelly Hill, Washington) in the late nineteenth/early twentieth century. Quintasket (Humishuma) was one of the first Native American women to publish a novel.