"Strong mental faculties and a vigorous constitution" were among the attributes of Zenas Leonard, according to the publisher of the 1839 edition of this book, which the Bison Books edition reproduces. In the spring of 1830, Leonard, a native of Clearfield, Pennsylvania, "ventured to embark in an expedition across the Rocky Mountains, in the capacity of clerk to the company. The last letter received by his parents, left him at the extreme white settlement [Independence, Missouri], where they were busily occupied in making preparations for the expedition to the mountains—from whence he promised to write at short intervals; but one misfortune after another happening to the company, he was deprived of all sources of communication—so that no tidings were received of him until he unexpectedly returned to the scenes of his childhood, to the house of his father, in the fall of 1835—after an absence of 5 years and 6 months!"
Written "in response to popular demand," so to speak, Leonard's account of these years, based in large part on "a minute journal of every incident that occurred," is recognized as one of the fundamental sources on the exploration of the American West. A free trapper until the summer of 1833, when he entered the employ of Captain B. L. E. Bonneville, Leonard was part of the group sent under command of Captain Joseph Walker to explore the Great Salt Lake region—an expedition that resulted in Walker's finding the overland route to California. The Narrative ends in August 1835, with Leonard's return to Independence.