In 378 =Theodosius the Great= proclaimed Christianity the religion of his Empire, and many temples in Lower Egypt were turned at once into churches; but the ancient Egyptian gods were worshipped as usual in Upper Egypt. =Marcianus= (A.D. 450-457) invaded Nubia and punished the Blemmyes and Nobadae for raiding Roman territory; they paid a huge fine, gave hostages for their future good behaviour, and made an agreement to keep the peace for one hundred years. In return they stipulated that they should be allowed to make pilgrimages annually to Philae, and to borrow the statue of Isis from time to time, so that they might take it about the country, and give the people the opportunity of invoking the protection and blessing of the goddess. In the first half of the sixth century the Nubians =embraced Christianity=, and =Silko=, king of the Nobadae, founded a kingdom having its capital at Dongola. During the reign of =Justinian= (A.D. 527-565) the hundred years’ truce came to an end, and the Blemmyes and Nobadae again began to give trouble. Justinian, believing that the cause of the revolt was the annual pilgrimage to Philae, sent his officer Narses thither, with strict orders to close the temples of Isis. Narses threw the priests of Isis into prison, confiscated the revenues of the goddess, and carried off the statues of the gods of Philae to Constantinople. In the reign of =Heraclius= the Persians, under Chosroës, invaded Egypt (A.D. 619), which they held for ten years. Owing to the desertion from the Persians of the Arab tribes, who had now attached themselves to the victorious troops of =Muḥammad the Prophet= (born at Mekkah, Aug. 20, A.D. 570, died in June, 632), Heraclius was able to attack the Persians, in Syria, and defeating them became master of Egypt once more. In =640= =ʿAmr Ibn al-Âṣî=, the general of the Khalîfa Omar, conquered Egypt, and thus the country became a province of the newly-founded Arab Empire.