When Was Zoroastrianism Founded?

The founding date of Zoroastrianism is uncertain. The religion was founded by the prophet Zoroaster in ancient Persia, but it is not known exactly when he lived. Estimates range from 1200 BCE to the 6th century BCE. All that is known for certain is that Zoroastrianism existed by the time Iran was unified under Cyrus II the Great (c. 590-529 BCE).