After 638, however, Christians suffered many persecutions. Christian shrines were repeatedly ransacked and defaced by the successors of Umur, and there was great persecution all around. The most deadly persecution occurred during the time of the Fatamid Al-Hakim bi-Amr Allah (1007–1009), a schizophrenic, named the "Nero of Egypt" for his merciless acts. He persecuted ferociously both Christians and Jews. He ordered that in public Jews were to wear masks representing the head of an ox and bells around their necks; Christians were to wear mourning apparel and crosses one yard in length. Also, Al-Hakim ordered the destruction of the Church of the Holy Sepulchre. In the eleventh century, the Caliph Ali az-Zahir, under a treaty with Byzantium, permitted the reconstruction of the shrines.