Lithograph entitled: "Life on the prairie. The trappers defense. Fire fight fire." The North American fur trade was a central part of the early history of contact between European-Americans and the native peoples of what is now the United States and Canada. The pelts in demand were beaver, sea otter and buffalo, as well as occasionally deer, bear, ermine and skunk. In the fall, when prairie grasses were dry and flammable, the native American Indians used fire as a bison-hunting technique. Once they found a herd, hunters would partially encircle it with a large, C-shaped ring of fire. The hunters would then station themselves at the open end of the "C" and shoot the bison as they attempted to escape the flames. They taught the technique to frontiersmen and trappers.