Mountain men were most common in the North American Rocky Mountains from about 1810 through to the 1880s (with a peak population in the early 1840s). Approximately 3,000 mountain men ranged the mountains between 1820 and 1840, the peak beaver-harvesting period. While there were many free trappers, most mountain men were employed by major fur companies. The life of a company man was almost militarized. The men had mess groups, hunted and trapped in brigades and always reported to the head of the trapping party.
This man was called a "boosway", a bastardization of the French term bourgeois. He was the leader of the brigade and the head trader.