respond to threats in the East and therefore Diodotus, who had begun pushing for his independence in c. 245 BC, abandoned hopes of remaining part of the Seleucid Empire and declared himself king, thus establishing what is now known as the Greco-Bactrian Kingdom. Margiana was conquered by the Parthians under Mithridates I of Parthia in c. 170 BC. The defeat of the Yuezhi people in 175 BC caused many Yuezhi to flee westwards, displacing the Saka as a result, leading to a mass movement of Saka and Yuezhi towards Sogdia and Bactria. Around 140 BC the Saka invaded Parthian territory through Margiana, venturing as far as Media in central Iran and continuing to harass the Parthians until 124 BC, in the course of which they defeated and killed two successive Parthian kings. The Yuezhi, who had settled in Sogdia along the Oxus, controlled Margiana until 115 BC when Mithridates II of Parthia re-established control over the east, forcing the Yuezhi to move south into Bactria. In 53 BC, 10,000 Roman prisoners captured by the Parthians after the Battle of Carrhae in Upper Mesopotamia were settled in Antiochia in Margiana. The Yuezhi went on to conquer the remaining Greek territories in Paropamisadae and establish the Kushan Empire. Post-Hellenistic period The Kushans returned to Margiana in the 1st century AD and helped the satrap Sanabares declare himself king who ruled from ca. 50 AD to 65 AD. At the onset of the 3rd century AD, Margiana had been restored as a vassal of the Parthian Empire, but continued to exist as a "virtually independent state". After Ardashir I's victory over the last Parthian king, Artabanus V, at the Battle of Hormozdgān in 224 AD, Margiana, ruled by a certain king Ardashir, submitted to Ardashir I and accepted vassalage. The vassal kingdom was permitted to continue minting its own coinage until it was formally annexed by Shapur I in c. 260 AD who granted control of Margiana to his son, Narseh, as part of the province of Hind, Sagistan and Turan. In the fifth century, during the reign of the Sasanian king Bahram V, Margiana and the northern territories were invaded and plundered by the Hephthalites, also known as the White Huns. Bahram, after initially sending an offer of peace, led a surprise attack on the Hepthalites and massacred them whilst they camped and then pursued them as they attempted to flee back