range and lifestyle of these groups. This transition was still underway when Europeans arrived. According to their oral tradition, the Kutenai people originated to the east, and moved onto the plateau in late pre-historic times. European contact Outside influences began changing life on the plateau decades before the first direct contact with Europeans. There is strong evidence the smallpox epidemic of the 1770s spread across the plateau region, greatly reducing the population. Members of the Lewis and Clark Expedition were the first Europeans to encounter plateau natives, followed a few years later by Alexander Ross and David Thompson. All commented on the dress, diet and generally peaceful nature of the inhabitants. In the following decades, several trading posts were established in the area, including the long-lived Fort Nez Perce, Fort Colville, Fort Okanogan, and Fort Kamloops. Several more epidemics hit the area with the Lower Columbia area being the hardest hit. Some Chinook and Kalapuya groups saw a 90% reduction in population at this time. The 1862 Pacific Northwest smallpox epidemic devastated the coast as well as some parts of the interior. While there was some minor violence, serious armed conflicts did not begin until the mass migration of European Americans to the southern portion of the plateau region, starting in the 1840s. Through a series of treaties and conflicts, including the Cayuse War, Yakima War, Coeur d'Alene War, Modoc War, and Nez Perce War, natives on the southern plateau were confined on reservations and their traditional lifestyle was largely disrupted. Tribes and bands Plateau peoples generally self-identified by their wintering village or band, as opposed to a tribe. Intermarrying between groups was common and in many cases encouraged. Different groups shared hunting and foraging ranges. After European contact, natives were classified into tribes led by chiefs, in order to facilitate negotiation and land settlements. Commonly recognized plateau tribes include the following: Chinook peoples Cathlamet, Washington Clackamas, Oregon Clatsop, Oregon Kathlamet Multnomah, Oregon Wasco-Wishram, Oregon and Washington Watlata, Washington Interior Salish Chelan Coeur d'Alene Tribe, Idaho, Montana, Washington Entiat, Washington Flathead (Selisch or Salish), Idaho and Montana Bitterroot Salish Kalispel (Pend d'Oreilles), Washington and Montana Lower Kalispel, Washington Upper Kalispel, Montana In-SHUCK-ch, British Columbia (Lower Lillooet) Lil'wat, British Columbia (Lower Lillooet) Methow, Washington Nespelem, Washington Nlaka'pamux (Thompson people), British Columbia Nicola people (Thompson-Okanagan confederacy) Okanagan, British Columbia and Washington Sanpoil, Washington Secwepemc, British Columbia (Shuswap people) Sinixt (Lakes), British Columbia,