As the expedition was to establish the first official contact between the United States and numerous nations across the territory, President Thomas Jefferson had directed the captains to pursue diplomatic goals. They were to try to establish friendly relations with as many tribes as possible, and to prepare them for the arrival of United States traders to the region. They were also to claim United States territorial sovereignty over the land, which had been occupied by Native Americans for thousands of years. The historic tribes had differing conceptions of property use than did the European Americans.