The name is the name of a people. The Asmat ethnic group, estimated around 70,000 within a wider regency population of about 120,000, have lived along these rivers and swamps since long before any European ship reached the Arafura Sea. Their traditional social structure was organized around ceremonial houses, kinship groups, and ritual cycles tied to ancestral spirits and to the complex ecology of the mangrove-swamp-forest mosaic in which they lived. Dutch colonization reached the region late and lightly compared to other parts of what became Indonesia. Missionaries arrived in the late nineteenth century. An administrative presence grew in the twentieth. The Asmat themselves remained, through colonization, handover, and integration, the cultural center of the place.

Between Indonesian independence in 1949 and 1962, Asmat continued as part of Dutch New Guinea while Indonesia and the Netherlands argued over sovereignty of the western half of the island. In 1962 the Netherlands transferred the territory to the United Nations Temporary Executive Authority, which passed it to Indonesia the following year. In 1969, the Act of Free Choice, a deeply contested process in which a small number of hand-picked delegates voted unanimously for integration, formally made Western New Guinea part of Indonesia. Asmat Regency itself was organized in 1969 as part of the early administrative effort to govern the new territory. It sat within Papua Province for decades, then moved into the new South Papua Province when that was created in 2022.

Asmat Regency began with eight districts in 2010 and expanded through subsequent reorganizations to 25. Tomor Birip and Sor Ep were the most recent additions, carved out of existing districts. The administrative centre is Agats, the elevated town on the Asewets River delta where the regency's government offices perch above the tides. Most other settlements are villages, kampung, scattered along the rivers: Atsy, Omandesep, Otsjanep, and dozens more that share the same essential architecture of houses on stilts, dugout canoes tied to the porch, and woodcarvings at the front door. Only a handful of the regency's 120,000 residents ever see a road, because the land itself resists road-building. Transportation is water, and has always been water.

If Asmat is known anywhere beyond Indonesia, it is known for its carvers. Shields, ancestor poles, paddle handles, ceremonial drums, and spirit figures of extraordinary complexity have moved from village festivals into museum collections in New York, Amsterdam, Basel, and Jakarta. The Metropolitan Museum of Art's Michael C. Rockefeller Wing contains major Asmat works; the son of a New York governor had been collecting in this very regency when he disappeared in 1961, a loss whose exact circumstances remain debated. The Asmat Museum of Culture and Progress in Agats, founded in 1973, houses masterworks and living practice together. The carvers themselves continue to work, cutting mangrove wood and ironwood into shapes that outsiders have collected for a century and that Asmat families still carry in their own ceremonies.

Asmat today sits between forces. Part of the regency lies inside Lorentz National Park, a UNESCO World Heritage Site protecting glacier-to-sea biodiversity. Other parts feel the pressure of logging, land-use change, and the administrative expansion that has reshaped the Indonesian provinces of Papua repeatedly in the last two decades. A serious famine struck in 2018; President Joko Widodo's response included a proposal to relocate remote communities into the capital at Agats, which met significant resistance. The population is growing. The woodcarving continues. The question, asked differently depending on who is asking, is what Asmat should look like in another generation. That question is not settled, and the people living in the swamps and on the boardwalks of its 25 districts are the ones still answering it.