Diodotus, the Seleucid satrap in Bactria, broke away and began issuing royal coinage, marking the emergence of an independent Greco-Bactrian kingdom (modern scholarship debates the exact year; c. 250 BCE is widely used).
Diodotus II took over the Bactrian throne after Diodotus I, continuing the early Diodotid dynasty and its coinage-based assertions of sovereignty.
Euthydemus I replaced the Diodotid line (often treated as a usurpation), inaugurating a new ruling house and setting the stage for conflict with the Seleucids.
During Antiochus III’s eastern campaign, Seleucid forces defeated Euthydemus I at the Battle of the Arius, opening the way to a direct assault on Bactria’s capital region.
After the Battle of the Arius, Antiochus III besieged Bactra (Balkh) for roughly two years; the campaign ended with a negotiated settlement that recognized Euthydemus as king, effectively confirming Greco-Bactrian autonomy.
Demetrius I, successor in the Euthydemid line, initiated major expansion across the Hindu Kush into northwestern India, developments that helped catalyze the later Indo-Greek political world.
Some Greco-Bactrian rulers (notably Agathocles and Pantaleon) issued early bilingual coinage, an important indicator of political and cultural engagement with Indian languages and audiences.
Eucratides I (“the Great”) took the throne amid intensified regional competition; his reign is central to the kingdom’s mid-2nd-century history and is dated by many scholars to about 171/170–145 BCE.
Archaeological research identifies a major destructive event at Ai Khanoum (a key Hellenistic city in Bactria) around 145 BCE, followed by a “post-palatial” phase of reoccupation and salvage.
Eucratides’ death (c. 145 BCE) contributed to political instability, weakening Greco-Bactrian capacity to hold territory against both internal rivals and external pressures.
Heliocles I (often dated c. 145–130 BCE) is commonly treated as the final Greco-Bactrian ruler to control territories north of the Hindu Kush, as nomadic incursions intensified.
Around 130 BCE, the Yuezhi (named in later sources as key actors in the region’s upheavals) overpowered remaining Greek authority in Bactria, ending the Greco-Bactrian kingdom as a functioning state in its original homeland.
Greco-Bactrian Kingdom (c. 250–125 BCE)
