After crossing the Continental Divide southeast of here on Aug. 12, 1805, Lewis camped with a Shoshoni band near here on Aug. 13-14. He needed to obtain Indian horses so his men could get from the upper Missouri to a navigable stream flowing to the Pacific, so he persuaded the Shoshoni to accompany him to the expedition's main camp east of the mountains. There he found that the Shoshoni chief was Sacajawea's brother. With horses and help from Sacajawea's people, Lewis and Clark came to this valley on Aug. 26 on their way north to the Lolo Trail and the Clearwater.