Abstract: This book brings to light the often neglected influence of Iranian ideas throughout the history of the world’s religions, from prehistory up to the present day. Originating as one of the Indo-European tribes of the Eurasian steppes in ancient times, Iranians share much of their mythology with the Greeks, Romans, Norse, and Hindus. From this shared past emerged the uniquely Iranian religion of Zoroastrianism, many of whose central beliefs were later adopted by Judaism, Buddhism, Christianity, and Islam. Living at the crossroads of East and West, Iranians were major players in the transmission of these faiths to central Asia, China, and the Indian Ocean basin.