Mithradates I Philhellene King of Parthia 
- Born: 195 B.C.
- Marriage: Unknown
- Died: 138 B.C. at age 57
Fifth king of Parthia, and the king who established Parthia as an ancient world power. He was the brother of Phraates I , and the son of Phriapatius . He was the father of Phraates II . See the genealogy chart .
We do not know the exact date of his accession, but he is mentioned by Justin [XLI.6] as a contemporary of Bactria's Eucratides and Antiochus IV Epiphanes. Antiochus IV campaigned in Iran to return the territories lost by Arsaces II .
Mithradates I may have campaigned into Tapuria and Traxiana shortly after succeeding to the throne. The death of Antiochus IV in 164 B.C. would certainly have reduced pressure on Parthia from the west. From 161 - 155 B.C. Mithradates waged a long war with Media, the success of which was long unsure. The best account appears to be that Timarkhos, Seleucid satrap of Media lost some territory in the area of Rhagae and farther east, to Mithradates I, while the Seleucid reconquest did not recover this land but did recapture Ecbatana . According to Justin, 1 Mithradates I had to fight many times in Media and Frye 2 believes it conceivable that the Seleucids held only the city and the lowlands to the west of Ecbatana at the time the relief at Herakles was carved, approximately 148 B.C.
The acquisition of Media opened the door to Mesopotamia for Parthian expansion into that fertile territory. 3 Mithradates entered the royal city of Seleucia and was recognized as King on or before July 8, 141 B.C. Before October 141 B.C., Mithradates sovereignty was acknowledged as far south as Uruk. But by December, incursions of the Sakae into Hyrcania forced him away to the east. Mithradates turned over military command to a Parthian commander and the remainder of his reign was occupied with campaigns in southern and central Parthia. 4 Mithradates was no sooner gone than Demetrius returned to the attack, joined by Elymais and Persis (and perhaps Bactrian troops), but Demetrius was soon captured and sent to Mithradates in Hyrcania. He was well treated, however, and given Rhodogune, Mithradates' daughter, in marriage. As punishment for joining Demetrius against the Parthians, Elymais was looted, where the temples of Artemis and Athena yielded "ten thousand talents." 5 Since the Parthians were established at Susa shortly after the death of Mithradates, that territory was probably added to the empire by him. 6 At his death, the Parthian empire included Parthia proper, Hyrcania, Media, Babylonia, Assyria, Elymais, Persis (?), and the districts of Tapuria and Traxiana.
Mithradates I died peacefully in 138/137 B.C., the first Parthian date fixed accurately by numismatic and cuneiform evidence. At his death, the Parthian empire included Parthia proper, Hyrcania, Media, Babylonia, Assyria, Elymais, Persis(?), and the districts of Tapuria and Traxiana.
With the name Mithradates, we may safely assume that worship of the god Mithra was officially sanctioned in Parthia. 7