History of Zoroastrianism from the Orientalist's Viewpoints

Although Zoroaster and some of his teachings have been familiar to the Western people from the ancient time, the academic study of the history and the culture of Zoroastrianism has begun since the beginning of the 18th century. From that time, especially after the great development of the philological study in the 19th century, Zoroastrian texts have been studied in an academic and critical way. However as Zoroastrianism is an ancient religion belongs to the distant past and its limited sources it has been almost impossible to portray a clear image of the history of the religion. Actually Zoroastrian sources belong to different ages, from the late second millennium B.C.E to the early Islamic period (7th C.E.). Naturally Zoroastrianism has been developed through this vast amount of time. The Western scholars has interpreted this development from the different viewpoints: some of them believe these different texts did not belong to a single tradition so we should speak of ancient Iranian religions (instead of a religion). However some scholars have tried to find a single tradition through these various texts and the other hold that there was a single tradition which had different manifestations in the different ages and areas.