Published online by Cambridge University Press: 19 November 2008
The 1980 Census of the Philippines (National Census and Statistics Office 1983) shows a multi-ethnic population speaking various Austronesian languages of the West Indonesian branch, which are not mutally intelligible but are clearly related to each other under various sub-groupings. The clearest divisions are the Northern Group and the Central Group, with the Northern Group situated in Northern and Central Luzon, and the Central Group located in Central and Southern Luzon, the Visayas, and parts of Mindanao (Zorc 1984). Smaller groups may be found in Eastern Mindanao (Eastern Mindanao Group), Southern Mindanao and Sulu (Sama-Bajaw Group), the area around Lake Lanao (Danao language group), Central Mindanao (the Manobo Group), and the islands of Palawan (the Palawanese Group) (cf., Pallesen 1985).