Coins, reliefs and
Babylonian astronomical diaries label Gotarzes as the son and heir of
Mithridates II (). According to a heavily damaged relief at
Behistun, Gotarzes had served as "satrap of satraps" under his father. After the death of his father, Gotarzes was proclaimed king at
Babylon. At his accession, Gotarzes appointed Mitratu as the general of
Babylonia. Gotarzes continued his father's policy by using their vassal, the
Artaxiad king of
Armenia,
Tigranes the Great (), as their representative in their efforts to extend their influence to
Syria and
Cappadocia. In 87/6 or 83 BC, Tigranes had seized Syria and
Cilicia. Gotarzes' had several wives, one of them, Asi'abatar (also spelled Ashiabatar), is known from tablets. The other one,
Ariazate, a daughter of Tigranes, was also Gotarzes' wife, and was probably the mother of Gotarzes' son
Orodes I. Gotarzes had two sister-wives, Siake and Azate. Gotarzes used the title of
Great King. Furthermore, like the rest of the Parthian kings, he used the title of
Arsaces on his coinage, which was the name of the first Parthian ruler
Arsaces I (), which had become a royal honorific among the Parthian monarchs out of admiration for his achievements. There is not enough evidence that indicate Gotarzes used the title of
King of Kings. Under Gotarzes I and Orodes I, Babylonian scholars notably followed wrote
cuneiform records in the same method that had been done in era of the Iranian
Achaemenid Empire. According to Shayegan, this was done to emphasize the association of the Parthians with their Achaemenid predecessors. Several hypotheses have been proposed regarding the end of Gotarzes' rule: According to Gholamreza F. Assar, Gotarzes' died in 87 BC and was succeeded by Orodes I, whose throne was shortly usurped by a brother of Gotarzes, named
Mithridates III. According to
M. Rahim Shayegan and Alberto M. Simonetta, Gotarzes died in 80 BC and was succeeded by Orodes I. Simonetta suggests that Mithridates III was not a contender of the throne during the reign of Orodes I, but that of Gotarzes, who eventually defeated Mithridates III in 87 BC. Shayegan, to the contrary of Assar and Simonetta, does not support the existence of Mithridates III, and has suggested that it was Gotarzes, and not Mithridates III, who defeated and captured the
Seleucid king
Demetrius III Eucaerus () in 87 BC. == Rock relief ==