Diodotus, Seleucid satrap of Bactria, rebelled against Antiochus II (about 255 BC) and became the founder of the Graeco-Bactrian kingdom (Trogus, Prol. 41; Justin xli. 4, 5, where he is wrongly called Theodotus; Strabo xi. 515). His power seems to have extended over the neighbouring provinces.

Arsaces, the chieftain of the nomadic (Dahan) tribe of the Parni, fled before him into Parthia and here became the founder of the Parthian kingdom (Strabo l.c.). When Seleucus II in 239 BC attempted to subjugate the rebels in the east he seems to have united with him against the Parthians (Justin xli. 4, 9). Soon afterwards he died and was succeeded by his son Diodotus II, who concluded a peace with the Parthians (Justin l.c.). Diodotus II was killed by another usurper, Euthydemus (Polyb. xi. 34, 2).

Of Diodotus I we possess gold and silver coins, which imitate the coins of Antiochus II; on these he sometimes calls himself Soter, "the saviour." As the power of the Seleucids was weak and continually attacked by Ptolemy II, the eastern provinces and their Greek cities were exposed to the invasion of the nomadic barbarians and threatened with destruction (Polyb. xi. 34, 5); thus the erection of an independent kingdom may have been a necessity and indeed an advantage to the Greeks, and this epithet well deserved. Diodotus Soter appears also on coins struck in his memory by the later Graeco-Bactrian kings Agathocles and Antimachus. Cf. AV Sallet, Die Nachfolger Alexanders d. Gr. in Baktrien und Indien; Percy Gardner, Catal. of the Coins of the Greek and Scythian Kings of Bactria and India (Brit. Mus.).

This entry was originally from the 1911 Encyclopedia Britannica.