(; ; ; , 'expanse of the Aryans') is considered in Zoroastrianism to be the homeland of the early Iranians and the place where Zarathustra received the religion from Ahura Mazda. The Avesta also names it as the first of the "sixteen perfect lands" that Ahura Mazda created for the Iranians.
Based on these descriptions, modern scholarship initially focused on Airyanem Vaejah in an attempt to determine the homeland of the Iranian peoples in general. Among these early attempts, the region of Khwarezm emerged as a likely locale. More recent scholarship, however, no longer agrees as to where Airyanem Vaejah might have been located or to what extent it is a mythological rather than a specific historical place.
Etymology and related words
The Avestan and the Middle Persian are compound terms where the first part is the adjective of Avestan or genitive plural of Middle Persian , respectively. Both these terms derive from a reconstructed Old Iranian term *āryah. This word also appears in Vedic Sanskrit as the self designation of the people of the Vedas. Within the context of Iran, however, the term *āryah and its derivatives in other Iranian languages simply mean Iranian. However, the exact meaning of the second part or is uncertain. Friedrich Carl Andreas derives it from a hypothetical Old Iranian *vyacah which he connects to Vedic Sanskrit "territory, region". On the other hand, Émile Benveniste connects it to the Avestan term (brandish, throw (a weapon)) which would be cognate to Vedic Sanskrit (vehement movement, irruption, flow) and, therefore, would give the meaning of "extent" or "expanse". It may also be related to Vedic Sanskrit (to move with a quick darting motion, speed, heave (said of waves)), suggesting the region of a fast-flowing river.
Zoroastrian tradition knows at least two other terms that associate the Iranian people with a geographical region. The first is found in the Avesta specifically in the Mihr Yasht. Vers Yt. 10.13 describes how Mithra reaches Mount Hara and overlooks the Airyoshayana (, 'Iranian lands'). This term is usually interpreted to refer to the entire land inhabited by Iranians which would make it an umbrella term for the Iranian regions mentioned in the following verse Yt. 10.14. However, Gherardo Gnoli notes the ambiguity of the text, such that Airyoshayana, like Airyanem Vaejah, may only refer to a specific country, one that occupies a prominent place among the Iranian countries from verses Yt. 10.13-14. The second term is the Middle Persian () and (). This word is the origin of the modern Persian term Iran. However, a possible Old Iranian origin has not been established and the term may be an innovation of the Sassanians.
In the Avesta
The earliest mentions of Airyanem Vaejah are found in the Avesta, in particular in the Vendidad and several of the Yashts. In the Yashts, Airyanem Vaejah is most prominently named in the Aban Yasht as the place where both Ahura Mazda and Zarathustra sacrifice to Anahita:
The other verses in which Airyanem Vaejah occurs in the Yashts follow the same structure, differing only in the deity to whom the sacrifice is offered. While in Yt. 5.104, Zarathustra is sacrificing to Anahita, this is changed to Drvaspa in the Drvasp Yasht (Yt. 9.25), and to Ashi in the Ard Yasht (Yt. 17.45). In the Vendidad, however, Airyanem Vaejah appears as the first of the sixteen best lands and countries that Ahura Mazda had created for the Zoroastrian community:
This connection between Airyanem Vaejah and winter is further described in Vd. 2.20-23. In these verses, Ahura Mazda is meeting there with Yima and instructs him to build a shelter for the winter that Angra Mainyu would soon unleash upon the material world. The harsh description of Airyanem Vaejah in Vd. 1.3, however, seems to conflict with the positive assessment given in Vd. 1.1. This has led some to speculate that the third verse is a later insertion, while others think that it could be a fragment of an originally longer description, and the text in Vd. 1.3 refers only to the upper headwaters of the river Daitya.