Compléter introVersion en ligne introduction on ethic par Miftakul Alfiani 1 Batak is a term used to identify a number of closely related Austronesian ethnic predominantly found in North Sumatra , Indonesia speak Batak languages . The term is used to include the Karo , Pakpak , Simalungun , Toba , Angkola , and Mandailing are related groups distinct languages and traditional customs ( adat ) .