[3] Asmat people live in southern Papua, around the big rivers of Aswets, Bets, Pomats, Undir, Sirets, and Brazza, all of which flow to the Arafuru Sea (formerly: Irian Bay).

Because it was watered by many rivers, the land became very large swamps, which were not useful for agriculture and caused the Asmat people to be isolated for a long time.

[3] Asmat people can divided into several sub-ethnic groups, including Unisirau, Bismam, Simai, Emari-Ducur, Betch-Mbup, Kaimo, Safan, Brazza, and Joerat.

[7] The Momuna people live in Sumo and Dekai districts on both sides of the Brazza River in the lowland rainforest to the south.

[8] South of the Momuna, the Asmat people, known for their wood carvings and bark paintings, live along the lower reaches of the Brazza River[5][9] The river flows in the southern area of Papua with a predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).