Later we find the worship of Isis and of Cybele,the latter being especially flourishing, with large corporations of dendrophori (priests who carried branches of trees in procession) and cannofori (basketcarriers); the worship of Mithras, too, had a large number of followers.
Speculations about the Perso-Hellenistic Mithras appear to have been transferred to the Gnostic Abraxas.
Modified though never essentially changed, (1) by contact with the star-worship of the Chaldaeans, who identified Mithras with Shamash, god of the sun,(2) by the indigenous Armenian religion and other local Asiatic faiths and (3) by the Greeks of Asia Minor, who identified Mithras with Helios, and contributed to the success of his cult by equipping it for the first time with artistic representations (the famous Mithras relief originated in the Pergamene school towards the 2nd century B.C.), Mithraism was first transmitted to the Roman world during the 1st century B.C. by the Cilician pirates captured by Pompey.
Mithras, identified with Sol Invictus at Rome, thus became the giver of authority and victory to the imperial house.
Finally, philosophy as well as politics contributed to the success of Mithraism, for the outcome of the attempt to recognize in the Graeco-Roman gods only forces of nature was to make the Sun the most important of deities; and it was the Sun with whom Mithras was identified.