From this old Indian trail, later known as the Old Oregon Trail, Captain B,L,E, Bonneville's partner, on first sighting the river in May 1833, exclaimed “Les Bois! Les Bois! Voyes! Les Bois!” meaning “The Woods! The Woods! See! The Woods!” Captain Bonneville therefore named the stream Riviere Boise, and also indirectly the mountains and city.