The indigenous ethnic groups of the mountains are known collectively as Montagnards or Khmer Loeu, a term meaning "Highland Khmer". They are descended from neolithic migrations of Mon–Khmer speakers via southern China and Austronesian speakers from insular Southeast Asia. Being isolated in the highlands, the various Khmer Loeu groups were not Indianized like their Khmer cousins and consequently are culturally distant from modern Khmers and often from each other, observing many pre-Indian-contact customs and beliefs.