The modern Persian name of Iran (ایران) derives from the 3rd-century Sasanian Middle Persian ērān, where it initially meant "of the Aryans," and acquired a geographical connotation in the sense of "(lands inhabited by) Aryans." In both geographic and demonymic senses, ērān is distinguished from its antonymic anērān, meaning "non-Iran(ian)".

Ardashir I, also known as Ardashir the Unifier, was the founder of the Persian Sasanian Empire. He was also Ardashir V of the Kings of Persis, until he founded the new empire. After defeating the last Parthian shahanshah Artabanus IV on the Hormozdgan plain in 224, he overthrew the Arsacid dynasty and established the Sasanian dynasty. Afterwards, Ardashir called himself "shahanshah" and began conquering the land that he called Iran.