do so. Two names in the West The exonym Persia was the official name of Iran in the Western world before March 1935, but the Iranian peoples inside their country since the time of Zoroaster (probably circa 1000 BC), or even before, have called their country Arya, Iran, Iranshahr, Iranzamin (Land of Iran), Aryānām (the equivalent of Iran in the proto-Iranian language) or its equivalents. The term Arya has been used by the Iranian people, as well as by the rulers and emperors of Iran, from the time of the Avesta. Evidently from the time of the Sassanids (226–651 CE) Iranians have called it Iran, meaning the "Land of the Aryans" and Iranshahr. In Middle Persian sources, the name Arya and Iran is used for the pre-Sassanid Iranian empires as well as the Sassanid empire. As an example, the use of the name "Iran" for Achaemenids in the Middle Persian book of Arda Viraf refers to the invasion of Iran by Alexander the Great in 330 BC. The Proto-Iranian term for Iran is reconstructed as *Aryānām (the genitive plural of the word *Arya); the Avestan equivalent is Airyanem (as in Airyanem Vaejah). The internal preference for "Iran" was noted in some Western reference books (e.g. the Harmsworth Encyclopaedia, circa 1907, entry for Iran: "The name is now the official designation of Persia.") but for international purposes, Persia was the norm. In the mid 1930s, the ruler of the country, Reza Shah Pahlavi, moved towards formalising the name Iran instead of Persia for all purposes. In the British House of Commons the move was reported upon by the United Kingdom Secretary of State for Foreign Affairs as follows: The decree of Reza Shah Pahlavi affecting nomenclature duly took effect on 21 March 1935. To avoid confusion between the two neighboring countries of Iran and Iraq, which were both involved in WWII and occupied by the Allies, Winston Churchill requested from the Iranian government during the Tehran Conference for the old and distinct name "Persia to be used by the United Nations [i.e., the Allies] for the duration of the common War". His request was approved immediately by the Iranian Foreign Ministry. The Americans, however, continued using Iran as they then had little involvement in Iraq to cause any such confusion. In the summer of 1959, following concerns that the native name had, as one politician put it, "turned a known into