Persian religion was originally polytheistic and tied to nature, with Ahuramazda (ah-HOOR-uh-MAZ-duh) as the chief god. Around 600 B.C.E. the ideas of Zoroaster (zoh-roh-ASS-tuhr), a thinker and preacher whose dates are uncertain, began to gain prominence. Zoroaster is regarded as the author of key religious texts, which were later gathered together in a collection of sacred texts called the Avesta. He introduced new spiritual concepts, stressing devotion to Ahuramazda alone and emphasizing the individual’s responsibility to choose between the forces of creation, truth, and order and those of nothingness, chaos, falsehood, and disorder. At the end of time, the forces of order would win, and the victorious Ahuramazda, like the Egyptian god Osiris, would preside over a last judgment to determine each person’s eternal fate.

Zoroaster’s writings were communicated by teachers, and King Darius began to use Zoroastrian language and images. Under the protection of the Persian kings, Zoroastrian ideas spread throughout Iran and the rest of the Persian Empire, and then into central China. Zoroastrianism survived the fall of the Persian Empire to influence Christianity, Islam, and Buddhism, largely because of its belief in a just life on earth and a happy afterlife. Good behavior in the world, even though unrecognized at the time, would receive ample reward in the hereafter. Evil, no matter how powerful a person had been in life, would be punished after death. In some form or another, Zoroastrian concepts still pervade many modern religions and Zoroastrianism still exists as a religion.