<P> The Chinook tribe, which is not federally recognized, who live near the lower Columbia River, call it Wimahl in the Chinookan language, and it is Nch'i - Wàna to the Sahaptin - speaking peoples of its middle course in present - day Washington . The river is known as swah'netk'qhu by the Sinixt people, who live in the area of the Arrow Lakes in the river's upper reaches in Canada . All three terms essentially mean "the big river". </P> <P> Oral histories describe the formation and destruction of the Bridge of the Gods, a land bridge that connected the Oregon and Washington sides of the river in the Columbia River Gorge . The bridge, which aligns with geological records of the Bonneville Slide, was described in some stories as the result of a battle between gods, represented by Mount Adams and Mount Hood, in their competition for the affection of a goddess, represented by Mount St. Helens . Native American stories about the bridge differ in their details but agree in general that the bridge permitted increased interaction between tribes on the north and south sides of the river . </P> <P> Horses, originally acquired from Spanish New Mexico, spread widely via native trade networks, reaching the Shoshone of the Snake River Plain by 1700 . The Nez Perce, Cayuse, and Flathead people acquired their first horses around 1730 . Along with horses came aspects of the emerging plains culture, such as equestrian and horse training skills, greatly increased mobility, hunting efficiency, trade over long distances, intensified warfare, the linking of wealth and prestige to horses and war, and the rise of large and powerful tribal confederacies . The Nez Perce and Cayuse kept large herds and made annual long - distance trips to the Great Plains for bison hunting, adopted the plains culture to a significant degree, and became the main conduit through which horses and the plains culture diffused into the Columbia River region . Other peoples acquired horses and aspects of the plains culture unevenly . The Yakama, Umatilla, Palus, Spokane, and Coeur d'Alene maintained sizable herds of horses and adopted some of the plains cultural characteristics, but fishing and fish - related economies remained important . Less affected groups included the Molala, Klickitat, Wenatchi, Okanagan, and Sinkiuse - Columbia peoples, who owned small numbers of horses and adopted few plains culture features . Some groups remained essentially unaffected, such as the Sanpoil and Nespelem people, whose culture remained centered on fishing . </P> <P> Natives of the region encountered foreigners at several times and places during the 18th and 19th centuries . European and American vessels explored the coastal area around the mouth of the river in the late 18th century, trading with local natives . The contact would prove devastating to the Indian tribes; a large portion of their population was wiped out by a smallpox epidemic . Canadian explorer Alexander Mackenzie crossed what is now interior British Columbia in 1793 . From 1805 to 1807, the Lewis and Clark Expedition entered the Oregon Country along the Clearwater and Snake rivers, and encountered numerous small settlements of natives . Their records recount tales of hospitable traders who were not above stealing small items from the visitors . They also noted brass teakettles, a British musket, and other artifacts that had been obtained in trade with coastal tribes . From the earliest contact with westerners, the natives of the mid - and lower Columbia were not tribal, but instead congregated in social units no larger than a village, and more often at a family level; these units would shift with the season as people moved about, following the salmon catch up and down the river's tributaries . </P>

The grand canyon was formed by the continuous flow of the columbia river