possibility that the Indo-Aryans of Mitanni came from the Indian subcontinent as well as the possibility that the Indo-Aryans of the Indian subcontinent came from the territory of Mitanni, leaving migration from the north the only likely scenario. The presence of some Bactria-Margiana loan words in Mitanni, Old Iranian and Vedic further strengthens this scenario. Iranian Avesta The religious practices depicted in the Rigveda and those depicted in the Avesta, the central religious text of Zoroastrianism—the ancient Iranian faith founded by the prophet Zoroaster—have in common the deity Mitra, priests called hotṛ in the Rigveda and zaotar in the Avesta, and the use of a ritual substance that the Rigveda calls soma and the Avesta haoma. However, the Indo-Aryan deva 'god' is cognate with the Iranian daēva 'demon'. Similarly, the Indo-Aryan asura 'name of a particular group of gods' (later on, 'demon') is cognate with the Iranian ahura 'lord, god,' which 19th and early 20th century authors such as Burrow explained as a reflection of religious rivalry between Indo-Aryans and Iranians. Linguists such as Burrow argue that the strong similarity between the Avestan of the Gāthās—the oldest part of the Avesta—and the Vedic Sanskrit of the Rigveda pushes the dating of Zarathustra or at least the Gathas closer to the conventional Rigveda dating of 1500–1200 BCE, i.e. 1100 BCE, possibly earlier. Boyce concurs with a lower date of 1100 BCE and tentatively proposes an upper date of 1500 BCE. Gnoli dates the Gathas to around 1000 BCE, as does , with the caveat of a 400-year leeway on either side, i.e. between 1400 and 600 BCE. Therefore, the date of the Avesta could also indicate the date of the Rigveda. There is mention in the Avesta of Airyan Vaejah, one of the '16 the lands of the Aryans'. Gnoli's interpretation of geographic references in the Avesta situates the Airyanem Vaejah in the Hindu Kush. For similar reasons, Boyce excludes places north of the Syr Darya and western Iranian places. With some reservations, Skjaervo concurs that the evidence of the Avestan texts makes it impossible to avoid the conclusion that they were composed somewhere in northeastern Iran. Witzel points to the central Afghan highlands. Humbach derives Vaējah from cognates of the Vedic root "vij", suggesting the region of fast-flowing rivers. Gnoli considers Choresmia (Xvairizem), the lower Oxus region, south of the Aral Sea to be an outlying area in the Avestan