Eucratides I the Great (Koinē Greek: , Eúkratides Mégas) (reigned 172/171–145 BC) was one of the most important Greco-Bactrian kings. Eucratides overthrew the Euthydemid dynasty and restored the Diodotids to power. He fought against the easternmost Hellenistic and Indian rulers in India, holding territory in the Indus and as far as Barigaza until he was finally defeated by Menander and pushed back to Bactria. Eucratides minted a vast and prestigious coinage, suggesting a rule of considerable importance and prosperity. His son, Heliocles I, was the last Greek king to rule in Bactria, as the Yuezhi overran the country c. 120 BC. Biography Early life Eucratides was born c.204 BC in the Hellenistic city of Ai-Khanoum, to 'Heliocles' and 'Laodice' as depicted on various finds of his coinage. His parents were likely members of the ousted Diodotid dynasty. It is unclear exactly what background or motive Eucratides had, or whether he and his family held any positions of rank during the reigns of Euthydemus I and Demetrius I. Coup d'état Eucratides came to the throne by overthrowing the Euthydemid dynasty in Bactria, possibly when its king, Demetrius was conquering northwestern India. The king whom Eucratides dethroned in Bactria was probably Antimachus I. It is unclear whether Eucratides was a Diodotid Bactrian nobleman who raised a rebellion, or, according to the claims of some scholars, a cousin of the Seleucid king Antiochus IV Epiphanes who was trying to regain the Bactrian territory. The Seleucid claim is highly unlikely and has been discredited by modern historians, and it is believed that Eucratides mother, Laodice was solely of the Diodotid dynasty. Justin explains that Eucratides acceded to the throne at about the same time as Mithridates, whose rule is accurately known to have started in 171 BC, thereby giving an approximate date for the accession of Eucratides: Some of the coins of Eucratides represent his parents, where his father is named Heliocles, and his mother, Laodice, who is depicted wearing a royal diadem and therefore of royal descent. Narain and other modern authors propose that she was a daughter of Diodotus I. Having become master of Bactria after de-throning the Euthydemid dynasty, Eucratides was faced with a Parthian invasion which began when Demetrius I was conquering India. Having taken Tapuria and Margiana from Demetrius in about 170 BC, the powerful Mithridates I attempted to conquer Bactria itself but was checked by Eucratides who wisely