Persian was the earliest noted empire with monotheism - Zoroastrianism is a religion and philosophy based on the teachings of prophet Zoroaster (also known as Zarathustra, in Avestan). It was probably founded some time before the 6th century B.C. in Persia (Iran). The term Zoroastrianism is, in general usage, essentially synonymous with Mazdaism (the worship of Ahura Mazda, exalted by Zoroaster as the supreme divine authority).