Diodotus was initially satrap of Bactria, but became independent of the Seleucid empire around 255 BC, establishing the Greco-Bactrian Kingdom.

[1][2] His rule was recounted by Apollodorus of Artemita in the Parthian History, but this text is lost, and surviving literary sources only mention him in passing.

The nature of the Bactrian satrapy, traditionally assigned to an Achaemenid Crown Prince, suggests Diodotus' prominence.

According to some scholars, he may have later married a daughter of Antiochus II (as his second marriage);[6] although this is uncertain and Tarn's genealogical assertions are controversial.

Frank Holt argues that the secession should be seen as a gradual process in which Diodotus and other eastern Seleucid satraps aggregated ever more autonomy, rather than a single event.

[19] By contrast, Jens Jakobssen argues that Diodotus assumed independence suddenly in 246 or 245 BC, in the confusion of the Third Syrian War, during which it briefly appeared that Ptolemy III had conquered the Seleucid core territories of Syria and Mesopotamia.

",[25] while the geographer Strabo says: The Greeks who caused Bactria to revolt grew so powerful on account of the fertility of the country that they became masters, not only of Ariana, but also of India, as Apollodorus of Artemita says: and more tribes were subdued by them than by Alexander... Their cities were Bactra (also called Zariaspa, through which flows a river bearing the same name and emptying into the Oxus), and Darapsa, and several others.Diodotus continued to be hostile to the Parthians for the rest of his reign.

Justin emphasises Arsaces' precarious position, opposed by the Seleucids to his west and Diodotus to the east—he is unclear about whether this opposition was co-ordinated.

[12] Before archaeological evidence became available, it was generally assumed that the Parni conquest of Parthia had decisively cut Bactria off from contact with Seleucid authority and Greek culture.However, archaeological evidence makes clear that goods and people continued to move between Bactria and the Seleucid realm.

[citation needed] Diodotus died during the reign of Seleucus II, sometime around 235 BC, probably of natural causes.

[26] The new king concluded a peace with the Parthians and supported Arsaces when Seleucus II attacked him around 228 BC.

The reverse of these coins abandoned the Seleucid god Apollo in favour of a depiction of Zeus preparing to throw his thunderbolt.

The coinage thus clearly proclaimed Diodotus' authority, but retained some ambiguity about the extent of his independence from the Seleucids.

After a break, both mints produce coins with the younger portrait and with the legend now reading Ancient Greek: ΔΙΟΔΟΤΟΥ ('Of Diodotus', Series D and F).

There is a similar break to the silver and gold coins, after which the bronzes are issued with the legend Ancient Greek: ΔΙΟΔΟΤΟΥ ('Of Diodotus', 'Series H').

[35] There is no explicit evidence for this daughter's existence and the speculative nature of Tarn's genealogical reconstructions has been criticised in subsequent scholarship.