When the more than 300 members of the 1938-1939 Hagen-Sepik patrol launched their exploration into the mountainous and rugged territory of central New Guinea, the patrol was unaware of the human communities that they would encounter. Indeed, much of central New Guinea was assumed to be uninhabited. Current archeology shows that parts of central New Guinea has been inhabited for (at least) 17,000 years, and in their 19-month journey, the patrol repeatedly made contact with human communities.
This photograph was taken in 1938 after a contingent of the patrol entered the Oksapmin region. (Patrol members have the rifles.)
Appreciation to the National Library of Australia for providing permission to publish several early photographs in my in press book, Cultural Development of Mathematical Ideas. This photograph is from the papers of John Russell Black, ms. 8346, Series 3, Folder 13: no. 124.