The Eucratids were a Greco-Bactrian and Indo-Greek dynasty of approximately 12 kings, lasting between c.171 BC and 80-70 BC, according to numismatic evidence. The numismatic emblem which characterized it were the palm and the Dioscuri (Castor & Pollux by horse).
The dynasty began when its founder Eucratides overthrew an Euthydemid king in Bactria, probably Demetrios II, c.171 BC. Taking advantage of the rivalry between the different Euthydemid Indo-Greek states, he managed to lead wars across the Hindu-Kush and succeeded until he met king Menander. He was then defeated and pushed back to Bactria. There he lead campaigns against Menander but was murdered by his own son, soon-called Eucratides II. This event is indicative of the relationships in this dynasty, as it was the same in the opposing Euthydemid dynasty.
His death let the kingdom into civil war between several Eucratid pretenders to the throne, which weakened the state; Parthians and Yuezhei took advantage of this and the last Greco-Bactrian king Heliokles must have left the kingdom to nomads c.130 BC. Paradoxically the dynasty succeeded to take part of Indo-Greek kingdoms and thus continued its engine of warfare there, due to its rivalry with the Euthydemids. Even if some Eucratids like Philoxenos seemed to have been powerful after 130 BC, they never succeeded to reunite the whole Indo-Greek possessions.
The dynasty finally ended when the Indo-Saka Maues successfully invaded the Indo-Greek kingdoms c.80 BC, forcing both Indo-Greek dynasties to make alliance under king Amyntas.