TETRARCH. — Originally, and according to its etymology, the head of one of the four regions of a province, or also one who shared command with three others; a tetrarchy was the authority, office, or territory of a tetrarch.
Euripides (d. 406 BC) first mentions tetrarchy in reference to Thessaly. Strabo (d. AD 20) attests that each of the tribes of Galicia was governed by four tetrarchs. However, by the 8th century BC, a single chief commanded an entire tribe, though retaining the title of tetrarch, which later lost its original meaning and came to denote merely the ruler of a small region, inferior in rank to a king or an ethnarch (v.), though sometimes enjoying some of their privileges. In this sense, the title was frequently used by the Romans, especially for the petty states of Syria.
Herod (v.) the Great and his brother Phasael received the title of tetrarch from Antony (41 BC), governing Galilee and Judea respectively. In the New Testament, the title tetrarch is ordinarily applied to Herod Antipas (Mt 14:1; Lk 3:1; 9:7; Acts 13:1), though he is sometimes called king (Mt 14:9; Mk 6:14, 22, 25 ff.), doubtless in popular usage. Lk 3:1 likewise gives the title of tetrarch to Herod Philip, son of Herod the Great, since both Antipas and Herod Philip had each inherited one of the four parts of Herod the Great’s kingdom, while Archelaus had received the other two parts with the title of ethnarch. Lk 3:1 also mentions a Lysanias (v.), Abilene (v.).