Centuries before North America was colonized, Indian societies flourished on the shores of the Columbia River. The annual return of salmon provided nutrient-rich food, a valued commodity for barter, and spiritual renewal. Men fished and hunted while women gathered roots, bulbs, berries, and herbs, and preserved the harvest. As shrewd traders, they developed a bartering network across the West that drew crowds of Native peoples to summer gaming and trade fairs. Contact with Euro-Americans drastically changed life for Native Americans as explorers carried deadly diseases and, in the years that followed, settlers appropriated Indian lands. Under pressure, tribes reluctantly signed treaties in 1855, relinquishing their vast domain for reservations. Though their culture was altered, Northwest Indians retained fishing and gathering rights on their ancestral lands and remain independent sovereign nations.