They were reliable trading partners who appeared at Fort Union with regularity and who had developed the social relationships with the post’s residents that sustained consistent commercial activity.

This commercial relationship was the mechanism through which men like Denig developed their deep knowledge of Crow society.

Twelve years of regular contact — including extended periods when Crow camps were near Fort Union, trading expeditions to remote areas, and social visits that went beyond simple commercial transactions — gave Denig an understanding of Crow life that was unusually sophisticated by the standards of his era.

The specific commercial value of the trading relationship to both parties also created incentives for maintaining accurate knowledge of conditions in the field.