In mid-August 1805, the Corps of Discovery reached the end of navigation on the Missouri River system here after ascending as far as possible by boat into the upper reaches of a tributary they called Jefferson's River, the Beaverhead. Lewis and Clark had expected to obtain horses from Indians in the region for a portage across the mountains to the Columbia River drainage, but they had seen no Indians since leaving the Mandan village four months earlier as time for crossing before winter was slipping away. Lewis and three men went ahead of the canoes, crossed the Continental Divide, found a Shoshoni band who were Sacajawea's people, and returned to the forks of Jefferson's River to wait for Clark and the canoe party. There the party met Snake nation Indians, halted after dragging the canoes through shallow water, and arranged to borrow horses to carry their baggage to the Columbia River. Because no easy portage over the mountains could be found, they left the canoes behind while William Clark went ahead to learn whether the Salmon River was navigable and Meriwether Lewis remained in camp to prepare for the portage over Lemhi Pass. The men made pack saddles and harnesses from rawhide thongs, oar blades, and planks from storage boxes, sorted and packed equipment and supplies, cached some supplies and specimens three-quarters of a mile downstream, and secured seven canoes in a pond near the forks by sinking and weighting them with stone for the return journey. William Clark recovered the canoes and supplies on July 8, 1806, during the return from the Pacific.