الحاكم بأمر الله
According to Abu al-Makarim, writing in the last quarter of the twelfth century, Zacharias was the last Patriarch of Alexandria to send letters to the rulers of Nubia and Ethiopia, having been forbidden to do so by the Fatimid Caliph Al-Hakim bi-Amr Allah. Nevertheless, if the Caliph or his vizier received a letter from either ruler, it remained the duty of the Patriarch to write a reply.