Barbarians No More. Revisiting the Eastern Contributions to Early Greek Philosophy by Cristian Constantin Lupașcu (2023)
Indian priestly traditions are deeply tied to the Magi, who were absorbed into the subcontinent multiple times, so this might be historically insightful.
"The transition from mythological to philosophical knowledge occurs in Greek thought when it encounters these Magi. In this regard, we shall see that Plato had a special relationship with the Magi, and the Magi in turn held Plato in high regard. However, Plato’s example is by no means an isolated case. We have other equally famous examples of Greek philosophers who we are told went to study in Persia before Plato, namely Pythagoras and Democritus."
"Diogenes Laertius, in the Prologue to his Lives of the Eminent Philosophers, states that there are some who recognise that philosophy began with the barbarians and names the Persian Magi as being among them. He also informs us of two books, written by Aristotle, now lost. One in which he names the Magi as the first philosophers – On Philosophy, and one in which he deals specifically with magic – Magicus. For him, as for his contemporaries, magic was not sorcery, but the philosophy or wisdom of the Persian Magi. Astronomy, astrology, algebra, geometry, medicine and herbalism on one hand. But also their intimate knowledge of the divine."
On the Medean/Zoro Magi: "The distinguishing marks that set them apart from the other tribes were their dress, their vegetarian diet and their worship of atar - the aspect of the holy fire, the visible presence of Ahura Mazda. The practice of fire worship was the most obvious aspect noticed in their rituals, which is why they were often called πυρολάτρης (purolátrēs) in Greek, and in their native tongue atašparast - fire-worshippers or ātarvahšā - the fire kindlers. Although this refers to only one of the types of priestly designations of the followers of Ahura Mazda"
"Probably best known today from the New Testament narrative, the Magi were the main bearers of Zoroastrianism and its most important representatives. Their reputation was so widespread that even in Christianity, they are a source of legitimacy for the infant Christ. Enigmatic figures who often vacillate between the esteem of those who had knowledge of them and the mythologising of those who did not, the Magi were the ethnic and social priestly class of the Achaemenid Empire, like the Brahmins in Indian society or the tribe of the Levites in Jewish society. They were the ones in charge of performing the rituals and sacrifices in accordance with the tenets of their creed. At least from the reign of Darius I, which we know was a practising Zoroastrian, the Magi were the formal priesthood of the empire. They also comprised the most erudite social stratum of the Persians, serving as scribes, accountants in the empire's administration or advisors to the emperor or the satraps. They are addressed by the epithet of 'wise men', often from the East."
The author argues that ancient traditions describing Pythagoras' travels to the East should be taken seriously, and that similarities between Pythagoreanism and the Persian Magi, such as vegetarianism, ritual purity, secrecy, and concern for the soul, suggest meaningful intellectual influence rather than mere coincidence. Suggests similar influence on Democritus, Socrates and Plato.