Zoroaster (Old Persian: Zarathustra; in modern Persian Zardosht) is generally thought to have lived about the 11th or 10th century BCE. Zoroastrianism is a religion and philosophy based on the teachings of Zoroaster as prophet. The term Zoroastrianism is; in general usage; essentially synonymous with Mazdaism (the worship of Ahura Mazda; exalted by Zoroaster as the supreme divine authority).

In Zoroastrianism; the Creator Ahura Mazda is all good; and no evil originates from Him. Thus; in Zoroastrianism good and evil have distinct sources; with evil (druj) trying to destroy the creation of Mazda (asha); and good trying to sustain it. In some form; it served as the national- or state religion of a significant portion of the Iranian people for many centuries.