Iranian philosophy or Persian philosophy can be traced back as far as to Old Iranian philosophical traditions and thoughts which originated in ancient Indo-Iranian roots and were considerably influenced by Zarathustra's teachings. According to the Oxford Dictionary of Philosophy, the chronology of the subject and science of philosophy starts with the Indo-Iranians, dating this event to 1500 BC. The Oxford dictionary also states, "Zarathushtra's philosophy entered to influence Western tradition through Judaism, and therefore on Middle Platonism."