Johanna Nichols on Indo-Iranian languages

“The Iranian family, which was next to sweep across the steppe and deserts, finds its region of greatest diversity in the central Asian mountains, and its ancestral Indo-Iranian family finds its own greatest diversity in the mountain region from central Asia to northern India (i.e. Bactria- Sogdiana and parts just south).”

“Prior to the Turkic expansion, at the beginning of the Iron Age, Iranian spread from somewhere in the vicinity of Bactria, Sogdiana, and the eastern steppe to cover most or all of western central Asia and the entire steppe, much of the Near East at least to eastern Anatolia, and, at least intermittently, the Danube plain, where Slavic vocabulary and ethnonyms attest to a major Iranianization at about the fifth century AD, and where there is good archaeological evidence of a Scythian presence in the mid-first millennium BC...”