More widely spread and more powerful than the religion of Isis was the religion of Mithras. Into the details of its early history we may not now go, but we must limit ourselves to a few points only. Mithraism had its origin in Persia, yet it was greatly influenced by the ancient theology of the Chaldeans and by Babylonian astrology, as well as later by the more barbarous religions of Asia Minor, whither it was carried by Persian colonists during the last three centuries before the Christian era. The Romans first came into contact with it during Pompey’s campaign against the pirates of Cilicia in 67 B.C., but the soldiers seem not to have been greatly impressed at that time, for it was about a hundred and fifty years later that Mithraism began to be influential in the West. Soldiers, traders, and slaves all aided in its spread. For the most part it followed in the steps of the Syrian gods, with whom it was closely associated. Along the borders of the Roman Empire, at the military stations on the Danube, on the Rhine, and by Hadrian’s Wall in Britain inscriptions and ruined chapels still attest the popularity of the cult; there are few Roman military centers in Europe, outside of Greece, or in the African provinces, which have not given evidence of its existence. In the ports of Italy, Puteoli and Ostia, in Rome, and in all the chief cities of the West, traders and slaves introduced the Persian religion; and the cult attracted many Roman citizens; it found favor with the imperial house, especially from Commodus to Diocletian. In fact during the second and third centuries Christianity found in Mithraism its chief rival.