Proto-Iranians first emerged following the separation of Indo-Iranians, and are traced to the Bactria-Margiana Archaeological Complex, a Bronze Age culture of Central Asia. Aryan, (Proto-Iranian) tribes arrived in the Iranian plateau in the third and second millennium BCE, probably in more than one wave of emigration. Further separation (due to migration) of Proto-Iranians, into an “Eastern” and a “Western” group, is attested in the form of Avestan, an Eastern Old Iranian language that was used to compose the sacred hymns and canon of Zoroastrian Avesta. And Old Persian, which appears primarily in the inscriptions, clay tablets, seals of the Achaemenid era (c. 600 BCE to 300 BCE). Examples of Old Persian have been found in present-day Iran, Iraq, Turkey and Egypt.
Nomadic Iranian tribes settled across the Iranian plateau and by the 1st millennium BC, Medes, Persians, Bactrians and Parthians populated the western part, while Cimmerians, Sarmatians and Alans populated the steppes north of the Black Sea. The Iranian Pashtuns and Baloch began to settle on the eastern edge, on the mountainous frontier of northwestern India and in to what is now Balochistan. Others, such as the Scythian tribes spread as far west as the Balkans and as far east as Xinjiang.
The rules and ethics emanating from Zorasters teachings were strictly followed by the Achaemenids who introduced and adopted policies based on human rights, equality and banning of slavery. Zoroastrianism spread unimposed during the time of the Achaemenids and through contacts with the exiled Jewish people in Babylon freed by Cyrus, Zoroastrian concepts further propagated and influenced into other Abrahamic religions. The Golden Age of Athens marked by Aristotle, Plato and Socrates also came about during the Achaemenid period while their contacts with Persia and the Near East abounded. The peace, tranquility, security and prosperity that were afforded to the people of the Near East and Southeastern Europe proved to be a rare historical occurrence, an unparalleled period where commerce prospered, and the standard of living for all people of the region improved.