Indo-Iranian Comparative Linguistics

Indo-Iranian comparative linguistics compares Vedic Sanskrit and Avestan systematically, in vocabulary, grammar and inherited poetic formula, to reconstruct the common Indo-Iranian language and religious vocabulary the two traditions shared before Vedic religion and Zoroastrianism diverged from a shared ancestor. The German Indologist Rudolf von Roth argued the case in an 1846 essay on the literature and history of the Veda, insisting that Avestan could not be read only through the lens of later Zoroastrian tradition but had to be compared directly against Vedic Sanskrit as its closest linguistic relative, a program extended a few years later when Niels Ludvig Westergaard published critical editions of the Avesta that made that direct comparison practically possible for the first time.

The method recovers specific shared terms and formulas, for gods, ritual fire and cosmic order among them, that predate the split between Vedic and Zoroastrian religion, letting the atlas describe what the two traditions' vocabulary shows they inherited in common rather than treating Vedic religion and Zoroastrianism as unrelated systems that happen to resemble each other. The atlas draws on the discipline wherever a claimed parallel between Vedic and Zoroastrian religious vocabulary needs a linguistic rather than a merely thematic basis.