The Great Papuan Plateau is a karst landscape, its limestone bedrock sculpted by millennia of tropical rainfall into sinkholes, caves, and rugged terrain cloaked in lowland rainforest. The eastern portion alone, east of the Sioa River, covers roughly 525 square miles. A 1966 census counted just 2,100 people in this area, speaking at least five different languages. The dominant ethnic groups include the Bosavi, Hawalisi, and Onabasulu in the east, with the Etoro, Bedamuni, and Sonia farther west. The plateau's isolation preserved both its ecosystems and its cultural diversity so thoroughly that in 2006 the Kikori River Basin and Great Papuan Plateau were placed on UNESCO's tentative list of World Heritage Sites, recognized for well-preserved natural systems and culturally significant sites.

In 1934 and 1935, Australian colonial patrol officers Jack Hides and Jim O'Malley led the first Western expedition across the plateau, traveling from the Strickland River to the Purari River. They canoed up the Strickland and then the Rentoul River, abandoning their boats about five miles below the confluence of the river's two branches. From there they walked, traveling for several days along the south side of the river without seeing a single person or sign of habitation. Then they camped at the junction of the Sioa and Rentoul rivers, looking across the valley at three longhouses whose inhabitants seemed to take no notice of them. The next morning, Hides was confronted by a group who had crossed the river in the night. The encounter turned hostile. Hides was ambushed, and he fired on his attackers, killing between one and three people. The patrol eventually passed north over the Karius Range and out of the plateau.

In March 1936, Ivan Champion and Richard Archbold flew over the northern foothills of Mount Bosavi to plan a future expedition from the Bamu River to the Purari. The Bosavi people, seeing the aircraft and facing the subsequent overland expedition months later, responded by abandoning their longhouses and fleeing into the forest. Two years later, a government station was established at Lake Kutubu, opening new trade routes from the east that upended established patterns. Then World War II delayed further exploration, and during the pause a devastating measles epidemic swept through the plateau, severely reducing the populations of the Etoro and Onabasulu people. When a second administration patrol finally reached the plateau in 1953, led by C.D. Wren, it escorted not soldiers but petroleum geologists. The plateau sits atop significant oil and gas reserves, and a pipeline from the region to the port town of Daru has been under construction.

The missionaries who arrived in 1964 found communities shaped by centuries of isolation and decades of upheaval. The Seventh-day Adventist who settled with the Onabasulu departed when his dietary prohibitions proved incompatible with a culture where pork held deep significance. That same year, UFM International arrived in the Bosavi area, recruiting local workers to build an airstrip for a mission station. Anthropologist Edward Schieffelin, who lived among the Bosavi in the early 1970s, documented their culture in The Sorrow of the Lonely and the Burning of the Dancers, a title that captures something essential about this place: its beauty is inseparable from loss. The plateau's people had lived for generations in a world defined by rivers, forest, and the limestone beneath their feet. Within a single lifetime, they encountered aircraft, epidemics, oil prospectors, missionaries, and the insistent pressure of a world that had finally found them.