As the Arabs were materially assisted in their conquest of Egypt by the Copts, the new masters of the country treated the latter with great consideration for about 100 years; but, from A.D. 750 onwards, they persecuted their Christian subjects at intervals with great severity. The non-Christian inhabitants of the country embraced =Islâm=, or the doctrine of Muḥammad the Prophet, and, with the religion of the Muslims, the knowledge of the Arabic language spread throughout Egypt. It gradually superseded Egyptian, or Coptic, and about the end of the twelfth century it became the common language of the country, Coptic ceasing to be spoken except in monasteries and remote villages. In 642 the Arabs, under ʿAbd-Allah bin Sa’ad, occupied the Egyptian Sûdân, and ten years later they marched to Dongola, destroyed the church and the town, and levied an annual tribute, or =Baḳṭ=, consisting of 360 or 365 men upon the Nubians, which was paid with more or less regularity for nearly 500 years. On several occasions the Arabs invited the Christians of Nubia to embrace Islâm, but the latter steadily rejected the offer, paid their tribute, and continued to worship God according to the teachings of their Jacobite priests, who were appointed to their office by the Patriarch of Alexandria. Many hundreds of churches were built in the Sûdân between A.D. 540, when the Christian religion was established by Silko, king of the Nobadae, and 1450, when the Christian kingdom of Alwa, on the Blue Nile, was destroyed. During the greater part of these 900 years the Liturgy was recited in Greek, and the services were conducted after the manner laid down by the spiritual authorities in Alexandria. Certain Books of the Bible and various Offices were translated into =Nûbî=, the language of the country; but of these few remains are extant. [Illustration: PLATE LIII. Sepulchral tablet set up in memory of Apa Paḥomo, the head of a monastic settlement. On the right is a figure of Saint Victor, and on the left a figure of Saint Apakene. VIIth to Xth century, A.D. [Southern Egyptian Gallery, Bay 30, No. 1103.]]