king in Persia, king of the countries, Hystaspes’ son, Arsames’ grandson, an Achaemenid". An inscription in the Armenian city of Van by Xerxes I reads; Parthian and Sasanian usage The standard royal title of the Arsacid (Parthian) kings while in Babylon was Aršaka šarru ("Arsacid king"), King of Kings (recorded as šar šarrāni by contemporary Babylonians) was adopted first by Mithridates I (r. 171–132 BC), though he used it infrequently. The title first began being consistently used by Mithridates I's nephew, Mithridates II, who after adopting it in 111 BC used it extensively, even including it in his coinage (as the Greek BAΣIΛEΥΣ BAΣIΛEΩN) until 91 BC. It is possible that Mithridates II's, and his successors', use of the title was not a revival of the old Achaemenid imperial title (since it was not used until almost a decade after Mithridates II's own conquest of Mesopotamia) but actually stemmed from Babylonian scribes who accorded the imperial title of their own ancestors onto the Parthian kings. Regardless of how he came to acquire the title, Mithridates II did undertake conscious steps to be seen as an heir to and restorer of Achaemenid traditions, introducing a crown as the customary headgear on Parthian coins and undertaking several campaigns westwards into former Achaemenid lands. The title was rendered as šāhān šāh in Middle Persian and Parthian and remained in consistent use until the ruling Arsacids were supplanted by the Sasanian dynasty of Ardashir I, creating the Sasanian Empire. Ardashir himself used a new variant of the title, introducing "Shahanshah of the Iranians" (Middle Persian: šāhān šāh ī ērān). Ardashir's successor Shapur I introduced another variant; "Shahanshah of the Iranians and non-Iranians" (Middle Persian: šāhān šāh ī ērān ud anērān), possibly only assumed after Shapur's victories against the Roman Empire (which resulted in the incorporation of new non-Iranian lands into the empire). This variant, Shahanshah of Iranians and non-Iranians, appear on the coinage of all later Sasanian kings. The final Shahanshah of the Sasanian Empire was Yazdegerd III (r. 632–651 AD). His reign ended with the defeat and conquest of Persia by the Rashidun Caliphate, ending the last pre-Islamic Iranian Empire. The defeat of Yazdegerd and the fall of the Sasanian Empire was a blow to the national sentiment of the Iranians, which was slow to recover. Although attempts were made at restoring the Sasanian Empire, even with Chinese help, these attempts failed and