Batak is a collective term used to identify a number of ethnic groups found in the highlands of North Sumatra Indonesia. Their heartland lies to the west of Medan centred on Lake Toba. In fact the "Batak" include several groups with distinct, albeit related, languages and customs (adat). While the term is used to include the Toba, Karo, Pak Pak, Simalungun, Angkola and Mandailing groups, some of these peoples prefer not to be known as Batak.

Before they became subjects of the colonial Dutch East Indies government, the Batak had a reputation for being fierce warriors. Afterwards Christianity was embraced widely, and the HKBP (Huria Kristen Batak Protestan) Christian church is presently the largest Christian congregation in Indonesia.