The Dayak are an indigenous people to Borneo, most renowned for their tradition of head-hunting. The Dayak ethnicity covers more than 200 riverine and hill-dwelling ethnic subgroups, located principally in the interior of Borneo, each with its own dialect, customs, laws, territory and culture. Dayak languages are categorised as part of the Austronesian languages in Asia. The Dayak were animist in belief; however many converted to Christianity, and some to Islam more recently. Estimates for the Dayak population range from 2 to 4 million.