In the neighborhood of the Falls, Thompson had found that the Kootenay river bent sharply to the west and north. In this direction, he had traced its course to Kootenay lake, before the floods came on, compelling him to cross overland to his home under the guidance of the chief Ugly Head. To the south of the Kootenay was a ridge of mountainous country, intersected however, by well-marked Indian trails running north and south. These trails, he was told, led to another great river, parallel with the Kootenay and, like it, flowing mainly to the west. This river (now known as Clark's Fork) he made up his mind to explore. His point of departure was from Ugly Head's encampment, near the present site of Bonner's Ferry, Idaho. There he laid up his canoes, and borrowed horses from the Kootenays for the journey across country. A two day's ride brought him to Clark's Fork at the point where it expands to form Lake Pend d'Oreille. Here he was met by a large deputation of Salish Indians, who welcomed him with presents and gave him every assistance in finding a site suitable for the erection of a post. Their joy was easy to understand, for they were armed merely with a few rude lances and flint-headed arrows, utterly useless in warfare against the Indians of the plains. Thompson had guns, ammunition, and iron arrow-heads for trade, but he warned them that in order to procure these advantages, they must learn to be industrious in hunting for beaver and other furs, and cease spending their days and nights in gambling--the pet vice of the savage. This they eagerly promised to do. It was the end of September before he had finished the construction of his new post (Kullyspell House), and he followed it up, by constructing a second post, Salish House, sixty miles further east along the river. From Salish House, he had only to ride out to the great camp of the Salish Indians near Flathead lake in order to secure the promise of their trade. He was now thoroughly established along the whole course of Clark's Fork river. From information he had gathered, Thompson judged that both the Kootenay river and Clark's Fork were tributaries of the Columbia, and that if he followed them westward to their mouths he would strike that mighty river. From the unwelcome visitations he had experienced at the hands of the Piegans, he realized that the line of approach from the defiles of the Saskatchewan to his new trading post was exposed throughout its length to raids of the plainsmen through the easy passes of the mountains. He therefore attempted to explore Clark's Fork to its junction with the Columbia, hoping that from thence he might discover a route further west and less accessible to his foes.