Identification. The word "Siuai" originally applied to a cape on the southern coast of Bougainville, but it later came to identify a wider area of the coast, its hinterland, and the people who lived there.
Location. The Siwai occupy the center of the Buin Plain of southern Bougainville, North Solomons Province, Papua New Guinea. The area, which is 7°S and 155° W, is in the humid tropical lowlands, almost all of the population living below 200 meters above sea level. Some Siwais now live in urban areas in other parts of Papua New Guinea.
Demography. In prewar years, the Siwai population was around 4,500; by the mid-1970s it had grown to about 9,000 and by the late 1980s was probably about 13,000.
Linguistic Affiliation. The Siwai (or Motuna) language is a Non-Austronesian (Papuan) language similar to other inland South Bougainvillean languages such as Buin, Nagovisi, and Nasioi. There are trivial differences in language within the Siwai area.