Name of Iran

In the Western world, Persia (or one of its cognates) was historically the common name for Iran. In 1935, Reza Shah asked foreign delegates to use the term Iran, the historical name of the country, used by its native people, in formal correspondence. Since then, in the Western World, the use of the word "Iran" has become more common. This also changed the usage of the terms for Iranian nationality, and the common adjective for citizens of Iran changed from Persian to Iranian. In 1959, the government of Shah Mohammad Reza Pahlavi, Reza Shah Pahlavi's son, announced that both "Persia" and "Iran" could officially be used interchangeably.

The Modern Persian word Īrān (ایران) derives immediately from Middle Persian Ērān (Pahlavi spelling: ʼyrʼn), first attested in an inscription that accompanies the investiture relief of the first Sassanid king Ardashir I at Naqsh-e Rustam. In this inscription, the king's Middle Persian appellation is ardašīr šāhān šāh ērān while in the Parthian language inscription that accompanies the Middle Persian one the king is titled ardašīr šāhān šāh aryān (Pahlavi: ... ʼryʼn) both meaning king of kings of Iranians.

The gentilic ēr- and ary- in ērān and aryān derives from Old Iranian *arya- (Old Persian airya-, Avestan airiia-, etc.), meaning "Aryan", in the sense of "of the Iranians". This term is attested as an ethnic designator in Achaemenid inscriptions and in Zoroastrianism's Avesta tradition, and it seems "very likely" that in Ardashir's inscription ērān still retained this meaning, denoting the people rather than the empire.

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