"We were also fortunate enough to engage in our service a Canadian Frenchmen, who had been with the Chayenne Indians on the Black mountains, and last summer descended thence by the Little Missouri"

This quote is from Meriwether Lewis, who became part of the Lewis and Clark Expedition. He is referring to a Canadian Frenchmen who had actually been living with the Chayenne Indians in the Black Mountains. This Frenchmen had just recently descended from the Black Mountains by the Little Missouri River. This was a lucky occasion for the exploration, as the Frenchmen had the ability to supply them with important details about the area and individuals they would come across. He was likewise able to supply them with a guide to help them browse the unknown terrain. The Frenchmen's understanding of the location and individuals was indispensable to the exploration, as it permitted them to make educated choices and prevent prospective risk. The Frenchmen's existence was a terrific property to the exploration, and his understanding and experience was invaluable.