testimony by an entry in the chronicle of the Greek Orthodox Patriarch of Alexandria Eutychius of Alexandria, which states that in 719 AD the church of Nubia transferred its allegiance from the Greek to the Coptic Orthodox Church. After the official Christianization of Nubia, the Isis cult of Philae remained for the sake of the Nubians. The edict of Theodosius I (390 AD) was not enforced at Philae. Later attempts to suppress the cult of Isis led to armed clashes between the Nubians and Romans. Finally, in 453 AD, a treaty recognizing the traditional religious rights of Nubians at Philae was signed. By the seventh century, Makuria expanded and became the dominant power in the region. It was strong enough to halt the southern expansion of Islam after the Arabs had taken Egypt. After several failed invasions the new Muslim rulers agreed to a treaty with Dongola, called Baqt, to allow peaceful coexistence and trade, contingent on the Nubians making an annual payment consisting of slaves and other tributes to the Islamic Governor at Aswan; it guaranteed that any runaway slaves were returned to Nubia. The treaty was kept for six hundred years. Throughout this period, Nubia's main exports were dates and slaves, though ivory and gold were also exchanged for Egyptian ceramics, textiles, and glass. Over time the influx of Arab traders introduced Islam to Nubia and it gradually supplanted Christianity. After an interruption in the annual tribute of slaves, the Egyptian Mamluk ruler invaded in 1272 and declared himself sovereign over half of Nubia. While there are records of a bishop Timothy at Qasr Ibrim in 1372, his see included Faras. It is also clear that the cathedral of Dongola had been converted to a mosque in 1317. The influx of Arabs and Nubians to Egypt and Sudan had contributed to the suppression of the Nubian identity following the collapse of the last Nubian kingdom around 1504. A vast majority of the Nubian population is currently Muslim, and the Arabic language is their main medium of communication in addition to their indigenous Nubian language. The unique characteristic of Nubian is shown in their culture (dress, dances, traditions, and music). Islamic Nubia In the fourteenth century, the Dongolan government collapsed and the region was divided and dominated by Arabs. Several Arab invasions into the region and the establishment of smaller kingdoms occurred over the next few centuries. Northern Nubia