Zoroastrianism (also sometimes known as Mazdaism) was founded by Zarathushtra (Zoroaster) in Persia around 600 BC (although some scholars estimate as early as 1500 BC). Zoroastrianism combines elements of monotheism and dualism. Some modern scholars believe that Zoroastrianism had a large influence on Judaism and Manichaeism, and thus indirectly influenced Christianity and Islam.
Ahura Mazda (literally: "the Wise Lord" like the Sanskrit "Asura Medha"; later transcription: Ohrmazd, Ormazd or Ormus) is revered and worshipped by Zoroastrians as the good God. Opposed to Ahura Mazda stands Ahriman (Angra Mainyu), who in some traditions is Ohrmazd's twin brother. According to Zoroastrianism, the earth was created by Ormazd as a battlefield to fight Ahriman (where Ohrmazd is destined to win approximately 3000 years after Zoroaster, that is, circa AD 2400). Human beings have free will to choose between Ohrmazd and Ahriman, however once this choice is made it is impossible or nearly impossible to change. Those who align with Ohrmazd are believed to go directly to Heaven after death or resurrection (depending on the tradition), whereas those who align with Ahriman go to Hell for a period of time before then going on to Heaven. Unlike Manichaeism, Zoroastrianism does not associate matter with evil. On the contrary, material pursuits such as raising a family and creating wealth are considered to aid Ohrmazd. "Good thoughts, good words, good deeds" is a common slogan.
However, Zoroastrianism is not simply the purely ethical religion it may at first seem. Purification rituals are important, and Zoroastrians practise sacrifice as well as confession. Indeed a religious Zoroastrian must constantly be involved in a meticulous struggle against the contamination of death (which is associated with Ahriman) and of the many other causes of defilement, and against the threat - even in sleep - of demons. Fire is an important religious symbol, and once started a ritual fire must be kept continually burning. The dead are not buried or cremated, but left for vultures to eat in special temples for that purpose.
Small Zoroastrian communities survive in Iran and in India, totalling 140,000 followers. Iranian Zoroastrians are called Gabars (a name deriving from the Arabic word kaffir meaning infidel). Other small Zoroastrian communities exist in large cities in the United States.
Zoroastrians fled to India in large numbers after the defeat of the Zoroastrian Sassanid dynasty by Muslim Arabs in the 8th century. They were given refuge by Jadi Rana, king of Sanjan (the modern-day province of Gujarat) on condition that they abstain from missionizing local Hindus and marry only in their community. Although these strictures are centuries old, Parsis of the 21st century still do not accept converts and are endogamous.
The earliest English references to Zoroaster and the Zoroastrian religion occur in the writings of the encyclopaedist Sir Thomas Browne.