Zoroastrianism took shape among Iranian speakers and became the religion of the Persian empires. Its founder, Zarathushtra, cannot be securely dated and estimates range across a millennium. What survives of his own voice is the Gathas, a small group of hymns in an archaic language embedded in the Avesta and translated by M. L. West among others.
The system Mary Boyce reconstructs sets Ahura Mazda, the wise lord, as creator, with asha, truth and right order, opposed by druj, the lie. The Amesha Spentas, the bounteous immortals, are aspects of the creator and are also attached to the elements of creation, so that care of fire, water, earth, plants and cattle is a moral duty rather than a metaphor. The distinctive claim is that each person chooses, and that the choice bears on the outcome of the whole conflict.
Fire is the visible focus, tended in temples rather than worshipped, and the highest grade of fire is assembled from many sources and never allowed to go out. The dead are exposed rather than buried or burned, because a corpse would pollute earth or fire. Ritual purity on this account is not fastidiousness but participation in the maintenance of a good creation against an active corruption of it.