Sorry for my poor English. It's not my mother tongue.

Originally Posted by
Resurrection
'Word Iran is modern Persian so it cannot be used. Alternative 'Eran' is from much older times (antiquity). In Middle Ages the most common name was 'Aryanam' gaining popularity from about year 1000 AD. In any case using any Iran/Eran while historically also justifiable would cause significant confusion imho.
Can you inform your source? imho, Eran is accurate.
ARYANS
The name “Aryan” is the self designation of the peoples of Ancient India and Ancient Iran who spoke Aryan languages. Aryan is thus basically a linguistic concept, denoting the closely related Indo-Aryan and Iranian languages.
─ R. Schmitt, 「
ARYANS」, 『
Encyclopćdia Iranica』.
ĒRĀN, ĒRĀNŠAHR
ērānšahr properly denotes the empire, while ērān signifies “of the Iranians.”
……
In the Pahlavi books of the 3rd/9th century the early Sasanian terminology is clearly preserved, e.g., in the Kār-nāmag, where Ērān is only used in the phrase šāh ī ērān and the title ērān-spāhbed (ed. Antia, 12.16, 15.9); otherwise the country is always called Ērānšahr (3.11, 19; 15.22, etc.). The same is true of the book of Ardā Wirāz, (ed. Gignoux, 1.4), where ērān dahibed “the ruler of the Aryans” alone appears beside the geographical name Ērānšahr. In the Dēnkard, 7, the same distinction is generally made (with anērān also designating the Non-Aryans). Here the phrase ēr deh, plural ērān dehān, from the Pahlavi translation of the Yašts, is also occasionally used for the “Aryan land(s).” Nevertheless, the fact that Ērān was also generally understood geographically is shown by the formation of the adjective ērānag “Iranian,” which is first attested in the Bundahišn and contemporary works.
In early New Persian works, especially those depending on Middle Persian sources, the form ērānšahr alternates with šahr-e ērān, (e.g., Tārīḵ-e Sīstān, pp. 6 -7). The poet Farroḵī Sīstānī (d. 429/1037-38), or possibly a later copyist of his poems, still uses it in contrast to tūrān “land of the Turanians” (pp. 99, 256, n. 8). The territory of Ērānšahr, however, came in time to be restricted to the western part of the former empire. In Tārīḵ-e Sīstān (tr. pp. 17 ff.) it is said that “The total area was divided into four parts: Khorāsān, Irān (Ḵāvarān), Nīmrūz, and Bāḵtar [not “Bactria”]. Whatever is located toward the northern boundary is called Bāḵtar; whatever is located toward the southern boundary is called Nīmrūz; and the area in between is divided into two: whatever lies toward the eastern boundary is called Ḵorāsān, while whatever lies to the west is called Īrānšahr.” In the Nozhat al-qolub, (tr. Le-Strange, p. 34) it is even reported (from Eṣṭaḵrī) that “Arabian ʿErāq used to be called the Heart of Īrān-Shahr” (del-e ērānšahr). The general designation for the land of the Iranians was, however, by this time ērān (also ērān zamīn, šahr-e ērān), and ērānī for its inhabitants.
Once more, I'm sorry for my poor English.