At the time of the Parthian uprising in 238 BC, the currency circulating in northern Iran was similar to that of the rest of the Seleucid empire. The bashlyk while typically nomadic, was also a satrapal head-dress in the Achaemenian period; its diadem binding was retained by all subsequent Parthian princes for their numismatic portraits. As a result of the downfall of Antiochus at Magnesia, the Greek bonds on Parthia were again loosened and an independent currency became feasible. Mithradates I was largely responsible for the political expansion of Parthia and so most recent studies are in agreement that the coins now to be described were struck by this prince. The Susa coins imply that Mithradates had been supplanted there by some other king perhaps as early as 94 BC. Coming immediately after the issues of Mithradates II is a group of drachms and bronze. The dates on Tiridates' coins permit inferences to be drawn about calendrical usages in Parthia.