The people are a Sahaptin-speaking tribe that traditionally inhabited the interior Columbia River region of the present-day northwestern United States.

[6] Lewis and Clark also gave Yellepit a peace medal engraved with a portrait of President Thomas Jefferson, to be worn around the neck, and a small United States flag.

About five miles upriver from Yellepit's village on the confluence of the Snake River and the Columbia, Thompson ordered a pole be placed.

An attached letter to the pole claimed the territory for the British Crown and stated the NWC intended to build a trading post at the site.

Thompson's pole and letter were intended for the traders of the Pacific Fur Company, an American rival of the NWC.

Thompson found Yellepit very friendly and intelligent, and the chief encouraged the plan to set up a nearby trading post.

[9] When that party returned to the northern territory, they found that some members had been infected with measles, to which the Native Americans had no immunity.