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)".

Spāhbad is a Middle Persian title meaning "army chief" used chiefly in the Sasanian Empire. Originally there was a single spāhbad, called the Ērān-spāhbed, who functioned as the generalissimo of the Sasanian army. From the time of Khosrow I on, the office was split in four, with a spāhbad for each of the cardinal directions. After the Muslim conquest of Persia, the spāhbed of the East managed to retain his authority over the inaccessible mountainous region of Tabaristan on the southern shore of the Caspian Sea, where the title, often in its Islamic form ispahbedh, survived as a regnal title until the Mongol conquests of the 13th century. An equivalent title of Persian origin, ispahsālār or sipahsālār, gained great currency across the Muslim world in the 10th–15th centuries.