Batak, Bataks or Bataknese is a collective term used to identify a number of closely related Austronesian ethnic groups predominantly found in North Sumatra and parts of adjacent provinces, Indonesia, who speak the Batak languages. The term is used to include the Toba, Karo, Simalungun, Pakpak, Singkil (mainly in adjacent Aceh province), Angkola, Mandailing and related ethnic groups with distinct languages and traditional customs (adat)