Life In Iran

Proto-Iranians first emerged following the separation of Indo-Iranians, and are traced to the Andronovo culture. Proto-Iranian tribes arrived in the Iranian plateau in the third and second millennium BC, probably in more than one wave of emigration, and settled as nomads.
Further separation of Proto-Iranians into "Eastern" and "Western" groups occurred due to migration. By the first millennium BC, Medes, Persians, Bactrians and Parthians populated the western part, while Cimmerians, Sarmatians and Alans populated the steppes north of the Black Sea.
Other tribes began to settle on the eastern edge, as far as on the mountainous frontier of the north-western Indian subcontinent and into the area which is now Balochistan. Others, such as the Scythian tribes, spread as far west as the Balkans and as far east as Xinjiang. Avestan is an eastern Old Iranian language that was used to compose the sacred hymns and canon of the Zoroastrian Gathas in c. 1000 BC.