Carson began his adult life in 1829 as a mountain man. He trapped beaver about ten years for the fur trade. During these years, Carson became an "Injun killer" he was forced to kill many Native Americans to protect himself from attack, theft, and murder. Carson became known as one of the greatest of "Injun killers" through novels, newspaper accounts, and other media. When the fur trade died out in the 1840s, Carson looked for other work.