in addition to seeking protection during the winter, captains meriwether lewis and william clark spent much of this period on diplomatic efforts with the several native american tribes who lived near the fort. as the expedition established the first official contact between the united states and these nations, president thomas jefferson had directed the captains to pursue diplomatic goals. they were to try to establish friendly relationships 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.