On September 4, 1805, at Ross' Hole in Sula, Montana, William Clark wrote that the Salish people received the expedition friendly, threw white robes over their shoulders, smoked in the pipes of peace, and camped with them. The Lewis and Clark Corps of Discovery stayed at Ross' Hole for two days, visiting, recording Salish vocabulary, purchasing eleven horses, and exchanging seven others. After crossing the Salmon-Bitterroot divide, today's Idaho-Montana border thirteen miles south of Ross' Hole, they came down the north side to this place, where Meriwether Lewis and William Clark became the first whites to meet the Salish, allies of the Shoshones, whom they mistakenly called Flathead Indians.