The Grass Koiari occupy an ancestral territory of singular importance to modern Papua New Guinea—the forested hills and grassy valleys that lie east of Port Moresby, stretching from the Sirinumu reservoir area through the Goldie River corridor toward the coast, and into portions of the National Capital District. Their name distinguishes them from the closely related Mountain Koiari, who live farther inland at higher elevations. Both groups speak languages of the Koiarian family, though Grass Koiari and Mountain Koiari are not mutually intelligible. Grass Koiari (also called simply Koiari) is a Papuan language with two main dialects—Western and Eastern—and is considered a threatened tongue, as younger generations increasingly favor Tok Pisin and Hiri Motu, the southern lowlands lingua franca.
European contact came early to this region. London Missionary Society pioneer William Lawes was among the first to document the Koiari ethnologically, publishing observations as early as 1879. The colonial era brought missionaries and administrative change, and the gospel has been present in this area for well over a century. The most consequential intrusion of modernity, however, came when Australian colonial authorities built the Sirinumu Dam on Koiari customary land between 1958 and 1963—a massive reservoir that to this day supplies most of Port Moresby's drinking water and a substantial share of its electricity. The Koiari landowners agreed to the project but have since spent decades in an unresolved dispute with successive governments over compensation. With deep historical irony, the community whose land feeds water to the capital has at times lacked reliable access to clean drinking water themselves. The world-famous Kokoda Track, which runs through Koiari country, brings thousands of Australian and other trekkers through their territory each year, connecting this small people group to a story that resonates far beyond their homeland.
Proximity to Port Moresby sets the Grass Koiari apart from many of the other groups in this series. Rather than deep jungle isolation, they live in the orbit of the nation's capital, which means some community members hold wage jobs in the city, sell produce at markets, or participate in the tourism economy associated with the Kokoda Track and Sirinumu Lake. Coffee is grown in the Koiari area and milled through a locally owned company. The dam itself has shifted local economic patterns—the creation of the reservoir forced a transition away from traditional hunting and gathering toward fishing and small-scale farming, and tilapia from the lake has become part of the local livelihood.
Even so, the Grass Koiari remain grounded in customary life. Extended clan networks govern land ownership, marriage arrangements, and mutual obligation. Pigs retain ceremonial importance, exchanged at events of social and spiritual significance. Traditional dance and communal celebration mark the passages of community life. Elders hold authority in customary matters, and land is held collectively under hereditary customary title—a system the Koiari have deployed repeatedly in their long-running negotiations with the government over the dam. The landscape itself—rolling savannah-woodland, rivers, mountain foothills—defines the character of Grass Koiari identity in a way that the unceasing pressure of Port Moresby's expansion now threatens.
Most Grass Koiari identify as Christian, the result of well over a century of sustained missionary presence in the Port Moresby region. Protestant Christianity predominates, and church attendance and Christian ceremony are woven into village life. Yet a portion of the community continues to practice traditional ethnic religion, and documented research on the neighboring Motu, Koita, and Koiari peoples of the Port Moresby area confirms that beliefs in sorcery and magic have persisted alongside Christian profession into the contemporary era. This is not surprising—proximity to a major city does not dissolve the older spiritual world; in many cases urban pressures intensify it, as people face new uncertainties and reach for familiar sources of power and protection.
The traditional Koiari spiritual framework holds that the forces at work behind illness, misfortune, and death are personal—they belong to the realm of ancestral spirits and sorcery practitioners who can direct harm toward enemies or protect allies. Sorcery accusations in Papua New Guinea have led to violence, and the underlying belief that death is rarely natural but instead is caused by someone with power over the spirit world remains active in communities throughout the Port Moresby region. Where these convictions persist among Grass Koiari believers, they represent a faith in tension—Christ may be honored in church while the spirit world is consulted when crises arrive. A completed Bible in the Grass Koiari language is needed to give believers the full authority of Scripture to answer these deep fears with the truth of who Jesus Christ is.
The Koiari situation with the Sirinumu Dam illustrates a broader pattern of need—this people group has contributed enormously to the infrastructure of the nation's capital while receiving little in return. A 2023 memorandum of understanding between Water PNG and the Hiri Koiari District Development Authority signaled renewed attention to the problem of water access in Koiari communities, but clean drinking water, reliable sanitation, and accessible healthcare remain unmet needs for many villages. The encroachment of Port Moresby's expanding urban footprint on customary land creates ongoing displacement pressure. Secondary and tertiary education, though more accessible here than in many remote PNG communities, is still limited for many Grass Koiari young people. The Koiari language itself is at risk as Tok Pisin displaces it among younger generations, making the urgency of completing a Bible translation in Koiari even more acute before the language retreats further.
Pray that Grass Koiari believers would stand on the full authority of Jesus Christ over the spirit world—freed from the fear of sorcery and ancestral powers, trusting entirely in the Savior who has conquered death.
Pray for the Holy Spirit to send revival to Grass Koiari families and churches.
Pray for the swift completion of the Grass Koiari Bible translation, so that God's living word can speak in their own language before the language further recedes from community use.
Pray for just resolution of the long-standing land and water grievances surrounding the Sirinumu Dam—that the Koiari people would receive dignified treatment and genuine access to the clean water that flows from their own land.
Pray for Grass Koiari churches to grow in depth and maturity, producing disciple-making communities that reach their neighbors with the gospel rather than accommodating the spiritual compromises that have long shadowed PNG Christianity.
Scripture Prayers for the Grass Koiari in Papua New Guinea.
https://en.wikipedia.org/wiki/Grass_Koiari_language
https://en.wikipedia.org/wiki/Sirinumu_Dam
https://www.everyculture.com/Oceania/Koiari.html
https://endangeredlanguages.com/lang/2226
https://malumnalu.blogspot.com/2011/04/sogeri-remains-absolute-delight.html
https://www.thenational.com.pg/water-all-around-but-little-to-drink/
https://www.linkedin.com/pulse/water-png-provide-technical-assistance-hiri-koiari-supply-projects
Gabutu, Gaudi. "Sorcery and Magic According to the Motu, Koita and Koiari Peoples of Port Moresby." Catalyst 42, no. 2 (2012): 146–159.
Lawes, W. G. "Ethnological Notes on the Motu, Koitapu, and Koiari Tribes." Journal of the Royal Anthropological Institute 8 (1879): 369–377.
| Profile Source: Joshua Project |
