In the Baliem Valley in central New Guinea lived a Stone Age tribe which survived into the twentieth century – the Kurelu. Matthiessen joined the Harvard-Peabody Expedition of 1961which set out to study the tribe as unobtrusively as possible, living among the Kurelu for two seasons. The result was this classic account, not of the expedition but of a lost culture; the Kurelu's timeless rhythms of work and play, of warriorship, feasting and funerals. In Under the Mountain Wall Matthiessen illuminates the lives of the Kurelu's with respect and sympathy, capturing a culture untouched by civilisation and vanishing along with the wilderness lying beneath the dramatic peaks of the Snow Mountains.
"One thinks of Darwin's Voyage of the H.M.S. Beagle. But Matthiessen is a better writer than Darwin and infinitely more imaginative"
– Atlanta Journal