When the Bents first traveled to this area, they may have encountered elk, bighorn sheep, pronghorn, deer, grizzly bears, wolves, beaver, river otters, and huge herds of bison. Bison especially provided the region's native people with food, clothing, and shelter, and wildlife also sustained the trappers and traders who arrived in the 1800s. In the 1830s, beaver pelts and bison robes were valuable commodities, and Bent's Old Fort was one of the most important fur trading posts in the West. As bison numbers dwindled, the Native Americans who were the fort's customers found life more difficult, and the decrease of bison in the area was one of the factors that led to the abandonment of the fort in 1849. Today, few if any of these animals remain.