Marga is a term in Batak societies referring to a clan name. The term is derived either from the Sanskrit varga, meaning company, party, or group, or, more likely, from the Sanskrit marga, meaning 'road, way or path', referring to a people of 'one origin'.
Batak marga are patrilineal. Marriage in the same Marga is strictly forbidden by tribal law (adat) even between people only distantly related; but it is allowed and often even arranged between cousins of the maternal line (boru). After marriage, Batak women do not change their family (marga) name, but add "boru" to their birth name.
In Batak Toba mythology, Marga are traced to the common ancestor "Si Raja Batak" (The King of the Batak). In Karo mythology, the five Marga (Merga Silima) are defined in terms of matrimonial bonds, with no importance placed on a common ancestor myth. Simalungun have four basic marga, each seen as equal, and likewise with no common ancestor myth.