The best evidence about Sasanian royal ideology comes from the first century or so of the dynasty, and although it is possible to detect developments thereafter, the basic principles apply throughout the regime’s history. Shapur I was the first to claim the title ‘king of kings of Iran and non-Iran’, whereas his father, Ardashir, had contented himself with the title ‘king of kings of Iran’ only. The legitimation of the new royal dynasty in its own realm was the immediate task the early Sasanians had to face. The great official state inscriptions from the early Sasanian period do not conceal the newness of the dynasty. The Res gestae divi Saporis is a list of the exploits of Shah Shapur I on the so-called Ka‘ba of Zardusht,18 and traces the royal genealogy back three generations, through his father Ardashir to his grandfather Papak. On the Paikuli inscription, set up by Shah Narseh to commemorate his successful bid for supreme power and his victory over his nephew Bahram III (293), there is only one significant addition. The dynasty is called ‘the seed of the Sasanids’, elucidating to some extent the role of ‘the lord Sasan’, mentioned in the Res gestae divi Saporis as recipient of an honorary cult, but not explicitly as a forebear of the dynasty. None of the other remaining six inscriptions that allude to the genealogy of the Sasanian shahs adds anything of significance.19 The great pictures that accompany many of these inscriptions present the key elements of legitimate royal authority. In some, the shah and his entourage unseat their rivals in a dramatic joust; or foreign enemies demonstrate their submission – including in some scenes theRoman emperor, who arrives at speed to acknowledge Sasanian mastery, kneels before his conqueror or lies prostrate at his feet. The proper transfer of power at each accession is symbolised by grand ceremonies involving shah and court; and in some pictures, divine investiture is symbolised by the figure of Ahura Mazda or of Anahita handing over a diadem to the shah.20 The monuments present a self-fulfilling legitimation. Supernatural sanction for the Sasanian house is demonstrated by the sequence of royal victories through which the Sasanians have achieved power; royal gratitude for this divine support is displayed by the establishment of a series of ritual fires. No attempt is made to conceal the shah’s bellicosity, and this self-glorification in divinely sponsored aggression is repeated three times in the Res gestae divi Saporis. According to the ideology enunciated in this document, wars of conquest are the duty of a good shah and military success proves legitimacy.21 Externally, or at least with regard to the Roman empire, the only area for which we have evidence, Sasanian strategies for legitimation were slightly more complex. Victory was still crucial, but warfare ought to have some justification. In his Res gestae, two of Shapur’s three expeditions against the Romans are presented as responses to Roman aggression; one of the three versions of the inscription is in Greek, and its contents were probably proclaimed to the inhabitants of the Roman empire, or to its former inhabitants resettled in Iran.22 More significantly, three historians writing in the Roman empire – Cassius Dio (LXXX.3.3) and Herodian (VI.2.1–5) from the third century, Ammianus Marcellinus (XVII.5.3–8) from the fourth – record how Sasanian envoys presented territorial demands on the Romans in terms of the revival of the oldAchaemenid empire.23 The repeatedRoman refusal to return what rightfully belonged to the new dynasty was sufficient justification for war. If the Achaemenid heritage was important in their western diplomatic dealings, there is no evidence that it was significant for internal legitimation. Although Ardashir and Shapur I chose to glorify themselves atNaqsh-i Rustam, near Persepolis, a site rich in Achaemenid associations,24 the possible connection is not voiced in their public inscriptions. The site was chosen for its monumental and awe-inspiring nature; there is no evidence that those who beheld these monumentswere aware of their specific Achaemenid associations, or indeed of the pristine greatness of the Achaemenids themselves. The modern name of the site, Naqsh-i Rustam, with its reference to the hero of Iranian epic tradition, indicates the extent to which folk memory can misrepresent the true nature of such sites. When Shapur I refers to his ancestors’ domain in his Res gestae, this is merely to state that exiles from the Roman empire were settled in Iran on crown lands – in Fars, Khuzistan and Ashurestan. Again, this is neither evocation of the Achaemenid empire nor a claim to legitimation as their heirs.25 It has been alternatively suggested that the Sasanians’ claims to legitimation harked back not to the Achaemenids but to the Kayanids, the heroic mythical rulers of Iran long before the historical Achaemenids.26 However, this hypothesis is not supported in the inscriptions: Shapur I only traced his genealogy back to his grandfather Papak, and did not claim universal kingship before his own reign (he is the first ‘king of kings of Iranians and non-Iranians’).More striking is the absence of any allusion to the dynasty’s Kayanid origin in Narseh’s Paikuli inscription, precisely the context where self-designation as ‘the seed of the Sasanians’ invited a link with a more glorious house. Kayanid names such as Kavad and Khusro only enter royal nomenclature in the late fifth century and probably reflect a change at that time in strategies for dynastic legitimation. Furthermore, it is the mythological Kayanid link which eventually introduces into royal genealogies an Achaemenid element that had not been present before. This Achaemenid link was clearly derived from the Alexander romance, which became popular at the Sasanian court in the first half of the sixth century. The Sasanian genealogies relayed through Arabic and New Persian sources deriving from lost Pahlavi historiography reflect, as often, the conditions and traditions of the last century of Sasanian rule; little genuine knowledge was preserved.