Diodotus II Theos (Greek: , Diódotos Theós; died c. 225 BC) was the son and successor of Diodotus I Soter, who rebelled against the Seleucid empire, establishing the Graeco-Bactrian Kingdom. Diodotus II probably ruled alongside his father as co-regent, before succeeding him as sole king around 235 BC. He prevented Seleucid efforts to reincorporate Bactria back into the empire, by allying with the Parthians against them. He was murdered around 225 BC by the usurper Euthydemus I, who succeeded him as king. Diodotus’ career was recounted by Apollodorus of Artemita in the Parthian History, but this text is lost, and surviving literary sources only mention him in passing. Thus, most details of Diodotus' life and career have to be reconstructed from numismatics. Background and co-regency The Seleucid empire gained control of Bactria and the surrounding regions between 308 and 305 BC and made it a satrapy (province) of their empire. Diodotus' father, Diodotus I ruled the region of Bactria as a satrap (governor) some time in the 260s BC and gradually drifted into independence during the reign of the Seleucid king Antiochus II Theos (261-246 BC). The process culminated in Diodotus I's proclamation of himself as king sometime between 255 and 245 BC. Coinage minted under Diodotus I derives from two separate mints. The coinage of one mint features a mature man on the obverse—generally identified as Diodotus I, while the obverse of coinage produced at the other mint depicts a similar, but younger, figure. Frank L. Holt proposes that the latter was Diodotus II. He suggests that Diodotus was entrusted with control of a portion of the realm that included the second mint. This arrangement would follow the model laid down by the Seleucids, who had made a practice of appointing the crown prince as co-regent and entrusting them with government of the eastern portion of the empire (including Bactria). The location of the region under Diodotus II's control is unknown; Holt tentatively suggests that he controlled the western region which was exposed to raids from Parthia and had his base at Bactra. Reign During his reign, Diodotus I had expelled the Parni king Arsaces I from Bactria. Arsaces had gone on to seize the region of Parthia from the Seleucids and carved out his own kingdom in what is now northeastern Iran. Diodotus I remained opposed to the Parni and thus aligned with the Seleucids. On his accession,