TETRARCH (reTpcipxijs), the ruler of a tetrarchy, that is, in the original sense of the word, of one quarter of a region. Such were the tetrarchies of Thessaly as reconstructed by Philip of Macedon and of Galatia before its conquest by the Romans (169 B.C.). In later times the title of tetrarch is familiar from the New Testament as borne by certain princes of the petty dynasties which the Romans allowed to exercise a dependent sovereignty within the province of Syria. In this application it has lost its original precise sense, and means only the ruler of part of a divided kingdom, or of a district too unimportant to justify a higher title. After the death of Herod the Great (4 B.C.) his realm was shared among his three sons: the chief part, including Judaea, Samaria and Idumaea, fell to Archelaus (Matt. ii. 22), with the title of ethnarch (Josephus, Antiq., xvii. n, 4); Philip received the north-east of the realm and was called tetrarch; and Galilee was given to Herod Antipas, who bore the same title (Luke iii. i). These three sovereignties were reunited under Herod Agrippa from A.D. 41 to 44. In the same passage of Luke mention is made of Lysanias, tetrarch of Abilene near Damascus, in the valley of the Barada.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)