Thus Spoke Zoroaster

Zoroaster, also known as Zarathustra, is regarded as the spiritual founder of Zoroastrianism. He is said to have been an Iranian prophet who founded a religious movement that challenged the existing traditions of ancient Iranian religion, and inaugurated a movement that eventually became a staple religion in ancient Iran. He was a native speaker of Old Avestan and lived in the eastern part of the Iranian plateau but his exact birthplace is uncertain.

source: Wiki