Meriwether Lewis, William Clark and the Corps of Discovery weren’t the only outsiders to mingle with the Mandans on the upper Missouri River in what is now North Dakota. Even before the Corps returned downriver in the summer of 1806, another expedition paid the Mandans a visit. Alexander Henry was employed by the North West Company, and he sought out the Mandans to acquire horses. He and two men left a trading post on the Red River at Pembina and traveled by horseback on muddy trails in the