Persian power gradually rose and can be considered to have peaked during the reign of Xerxes, from 486 B.C.E to 465 B.C.E. This is the time, also, when the portents of decline occured. When Xerxes' invasion of Greece failed, the military loss was of such calibre that the Persians never again undertook a major military operation against the Greek mainland - also, this signalled the defeatability of the Persian troops that had hitherto been continuously victorious. This was, however, not sufficient to dislodge the Persian Empire just yet. With Darius II Greece finally fell under Persian rule through several clever political and military actions - it was, however, not military superiority that conquered Greece, but exploitation of the Greek inter-city-state strife that allowed Persia to move in successfully. As the reign of Artaxerxes II came to a close during the last years of the 5th century B.C.E. the empire suffered a rise in anarchistic behaviours by small prinicipalities. This was, however, completely surppressed when the vicious reign of Artaxerxes III began. He crushed all rebellions and the empire reached its former glory as it had been under Xerxes little less than a hundred years earlier.

This Persian dominance ended with the rise of Alexander who with his superior army of phalanx, following the assassination of his father, Philip of Macedon, began to fulfill his dream for world conquest. With the Macedonian victory at Gaugamela on October 1, 331 B.C.E. the Persian empire essentially ceased to exist. However, the reign of Alexander was short lived, and with his death in Babylon on June 13, 323 B.C.E. another series of wars arose between his generals for dominance, as Alexander had left no heirs. In less than 20 years, Seleucus succeeded in gaining control, beginning the short reign of the Seleucid empire. This, empire, however, did not include all of the Persian empire - the eastern fronteirs west of the Indus were lost, as well as small kingdoms in Media, Armenia (in the southern Caucasus), Pontus and Cappadocia. For several years, the Seleucid kings attempted to maintain the empire, but, because of its great expanse, enemies had too many points of attack that the Seleucid armies could not maintain at once. However, eventhough constant war plagued the empire, Mazdaism, and what was now the cult of Mithra - that is Mithraism - gained its Hellenistic veneer and through the Greek veins of the empire, was able to spread and properly root itself in centers in Armenia and Cappadocia.

If one is to discount the ancient Aryan origins, then indeed, this is the time and place that Mithraism can be said to have it's birthing place. However, as eventhough throughout the following centuries, Mithraims maintained a thick Hellenic and Chaldaean skin, its inner mysteries remained fully Iranian in nature, and as such, the link between the Mithraism of the 4th century B.C.E. can not be severed with that of the ancient Aryan deity worship.

One of the most significant Hellenic contributions of this time was that of iconography. The Mithraic preists in step with the traditions of Mazdaism and Zoroastrianism did not utilizing symbolic representations of thier gods. This radically changed with the advent of Hellenic influences which culminated in a distinct iconography for the Mithraic followers. It can be surmised that at this time the images of the tauroctony, that is, the bull slaying, that form one of the central scenes within the later Roman mithraeums (real or artificial cave structures in which the Roman Mithraists worshipped) were being formed. Unfotunately, as so few documents have survived on Mithraism, save the passages from Porphyry (3rd century Greek historian), Dio Christosom (2nd century Greek philosopher) and the polemics of the early church fathers, the origins and nature of many of the Mithraic images that have survived can only be analyzed in terms of educated speculation. Some images can be traced back to their origins more effectively than others; we have for instance the birthing scene of Mithra. In Armenian legends Mithra was born in a cave of a virgin mother, Anaitis - which earlier legends posited as his sexual partner, altho, her personification as Ishtar, could have easily mutated in various fashions throughout the centuries; also, in Mazdian legend, as related to us by Porphyry, Mazdian was to have concecrated a special cave for the worship of Mithra; and it is known, symbollic caves were not uncommon in the ancient world. We also have the scene of the birth of Mithra from a rock or sea of water, the latter of which can be clearly traced back to Mazdian creation mythology.