Enga is geographically situated in the northern region of Papua New Guinea and was separated from the adjacent Western Highlands at the time of national independence in 1975.

The yalyakali, or "sky people," are fair-skinned and beautiful deities whose idyllic lives in the clouds mirror the agricultural and clan structure of the Raiapu below but lack the sadness of ordinary life.

Feachem states that "the remaining spirit beings (ghosts and demons) are an aggressive and bellicose group who are mercilessly engaged in an endless cycle of revenge and mischief."

A timongo is a spirit which leaves a human body upon death and wanders the forests as "a source of continual fear and alarm for the living," particularly the still-living members of their own immediate families, against whom they bear "bitter grievances."

Also living in the wild forests, as well as caves and pools, are evil, carnivorous demons known as pututuli, which can change their shape but are often seen as being extremely tall with two-fingered claws.

Only a fifth of the 5000 Australian-made Self Loading Rifles and half of the 2000 M16's delivered to the Papua New Guinea Defence Force (PNGDF) from the 1970s to the 1990s were found in government armouries during an audit in 2004 and 2005.

The theft and smuggling of ammunition has also led to large numbers of casualties, leading to peace treaties being more difficult to obtain.

Prime Minister James Marape called it an act of domestic terrorism and stated that they would seek help from Australia to support policing and security in the region.