Although the Brooks Range was well known to the Inupiaq and Athabascan peoples who trekked through the region in pursuit of fish and game, the mountains remained unknown to outsiders until the last decades of the 1800s. Long after the United States purchased Alaska from Russia in 1867, the Brooks Range remained a blank spot on cartographers' maps. During the 1880s, however, officials in the United States government felt the need to map northern Alaska, if only to know more about the vast territory under their jurisdiction.
The first explorers to find their way to Alaska’s Interior – Lieutenant Frederick Schwatka and Lieutenant Henry Allen, both of the U.S. Army – mapped major waterways in Interior Alaska but did not reach far enough north to encounter the Brooks Range. Lt. Schwatka charted much of the Yukon River, and although Lt. Allen did not cross what is today the boundary of Gates of the Arctic National Park and Preserve, at the end of his 1,500 mile journey he did manage to map the upper course and tributaries of the Koyukuk River based on information from a Koyukon Indian elder. These early attempts soon inspired others to investigate Alaska’s last terra incognita.