The Sasanian Empire was important for a number of reasons. Besides being the last of three great Persian dynasties, they carried on many Persian cultural traditions relating to religion and kingship. The Sasanians fostered and promoted the native religion of Zoroastrianism to the point of persecuting other religions from time to time. It was during the Sasanian period that the numerous Zoroastrian hymns, prayers, and rituals were collected under one book, known as the Avesta. The Sasanians also had a profound global influence through one of the most idiosyncratic religions of the ancient Middle Eastern world: Manichaeism. Like Zoroastrianism, the Manichaean religion has a rich history, as seen in its interactions with early Christianity and its unparalleled emphasis on secrecy. These exceptionally mysterious elements have appealed to the curiosities of thousands of scholars who have studied the development of this ancient belief system and where it came from. Manichaeans primarily revere the teachings and life of their prophet Mani who formed a synthesis of various religious traditions contemporaneous to his life. Although hardly a well-known religion in modern days (and, quite likely, an extinct religion in terms of practitioners), the Manichaean religion is an important witness to the development and interchanging ideas seen in early Iranian and Christian religion. Similarly, thanks to the Sasanians' efforts with regard to religion, modern scholars know much more about Zoroastrianism than they would have if the religion continued to disseminate orally. Their efforts also protected Zoroastrian knowledge in later years after the dynasty was long gone and Islam became ascendant in Persia. Moreover, the Sasanians' spread into India meant that there were syncretic developments between Zoroastrianism and Indian mythology and religious practices, including not just Hinduism but also Sikhism, Jainism, and Buddhism.
