In 1806, explorer David Thompson set out from Saskatchewan to find the source of the Columbia. He crossed over the Canadian Rockies through Howse Pass and eventually arrived on the banks of the Kootenay, which he thought to be the Columbia. Thompson traveled down the river a ways but turned back when he was attacked by Native Americans. The following year, Thompson, his family, and several men made another attempt at finding the Columbia. They crossed over the Rockies at a more northerly spot and traveled down the Blaeberry River to the Columbia, eventually discovering Columbia Lake and establishing there the trading post Kootenae House. In the spring of 1808, he set off down the Kootenay River, this time reaching present-day Montana and Idaho where he established Kullyspell House and Saleesh House, trading posts on Lake Pend Oreille and the Clark Fork, respectively. After spending a winter in Montana, he tried to reach the Columbia by traveling down the Pend Oreille River but failed in this attempt, eventually returning to Kootenae House via the Kootenay River northwards the following spring.