Name of Iran
Historically, Iran was commonly referred to as "Persia" in the Western world. Likewise, the modern-day ethnonym "Persian" was typically used as a demonym for all Iranian nationals, regardless of whether or not they were ethnic Persians. This terminology prevailed until 1935, when, during an international gathering for Nowruz, the Shah of Iran, Reza Shah Pahlavi officially requested that foreign delegates begin using the endonym "Iran" in formal correspondence. Subsequently, "Iran" and "Iranian" were standardised as the terms referring to the country and its citizens, respectively.
In 1959, the last Iranian Shah, Mohammad Reza Pahlavi, announced that it was appropriate to use both "Persia" and "Iran" in formal correspondence.
A variety of scholars from the Middle Ages, such as the Khwarazmian polymath Al-Biruni, also used terms like "Xuniras" (Avestan: Xvaniraθa-, transl. "self-made, not resting on anything else") to refer to Iran: "which is the center of the world, [...] and it is the one wherein we are, and the kings called it the Iranian realm."