At the beginning of the study period, The Nile Valley (Egypt and Sudan) hosts one of the oldest agricultural civilization on Earth. The basic pattern of human movement here is simple - people go up ad down the Nile (As Holtz points out, "Going off to the side ain't so much fun."). Only at the end points of this route do migration routes fan out into the sub-Saharan African interior in the south and Libya and the Fertile Crescent in the north. If your ancestors were from anywhere along the Nile in CE 500, assume their ancestors they could have been from anywhere else along it in CE 1.
At the beginning of the study period, Egypt was becoming the primary bread-basket of the Roman Empire and Sudan was home to the native Sudanese kingdom of Meroe. Although Meroe was rather provincial, administrators, soldiers, slaves and others moved in and out of Egypt and throughout the Empire. Thus, if your ancestors were in Egypt in CE 500, they could have been from anywhere in the empire in CE 1.
CE 642 - Islam: The new Islamic state quickly conquers Egypt, introducing an Arab ruling class. The Muslims are unable to move into Sudan, however, which maintains its independence for several centuries. Although Arab administrators were only a thin upper crust, Egypt was an integral part of the Umayyad and Abbasid Caliphates. During this period, nomadic Arab tribes began moving freely in Egypt. Thus, if your ancestors were in Egypt in CE 100, they could have been from anywhere in the Asian portions of the Umayyad and Abbasid dominions (Arabia, the Fertile Crescent, Iran) in CE 500.
Tenth Century - The Fatimids: The Fatimids were a Shiite dynasty that arose in the Maghrib (modern Tunisia, Algeria, and Morocco.) The Fatimids seized Egypt, making Cairo their capital, and severing it from the Sunni Abbasid Caliphate. Two things made the Fatimids interesting demographically:
Twelfth Century - The Mamlukes: The Fatimids were politely overthrown by Salah-ud-Din al Ayyubi (Saladin of the movies) in 1160. This is interesting to us because his army consisted largely of Turkic soldiers whose ancestors had only recently migrated into Iran and the Fertile Crescent from Central Asia. In those places, they would go on to found the Seljuk Empire. In Egypt, they became the core of the Mamluk dynasty. "Mamluk" is Arabic for "servant." The Mamluks were originally a slave corps of soldiers, officers and administrators who managed to recognize that they wielded the real power in their land and take over. Thus, if your ancestors were in Egypt in CE 1490, their ancestors could also have been from Iran, the Fertile Crescent and Central Asia in CE 1000. When Egypt became part of the Ottoman Empire in 1517, little changed, as the old Mamluk servant-aristocracy served as Ottoman viceroys.
Fourteenth Century - Sudan embraces Islam: The Arab bedouin tribes of Egypt made stronger inroads into Sudan as its Christian government weakened. There was never a single Islamic "conquest" of Sudan, rather, during the fourteenth and fifteenth centuries, the Sudanese gradually converted while intermarriage with Arab nomads and traders produced a population that was Islamic, but distinctly African. Thus, if your ancestors were in Sudan in CE 1490, their ancestors could also have been from Egypt in CE 1000. The incorporation of Sudan into the Islamic fold facilitated a slave trade, in which people were captured in southern Sudan or adjacent regions (Chad, Uganda, etc.) and sold in Egypt and western Asia. Thus, if your ancestors were in Egypt in CE 1490, their ancestors could also have been from southern Sudan and points south in CE 1000.
Sixteenth Century - The Funj: The Funj were a semi-nomadic people from southern Sudan and Ethiopia who conquered and ruled central Sudan. Thus, if your ancestors were in Sudan in CE 1800, their ancestors could also have been from southern Sudan and Ethiopia in CE 1490.
1805 - Muhammad Ali: In 1796, Napoleon Bonaparte led the French army into Egypt. They were ejected, in large part through the efforts of Muhammad Ali, an ethnic Albanian Ottoman officer leading a contingent of Albanian troops. Muhammad Ali became Ottoman viceroy of Egypt and set it on a course of rapid modernization. His demographic effect:
Nineteenth century - Egyptian imperialism in Sudan: Having been modernized by Muhammad Ali, Egypt started to act like a modern power of the time, trying to join the Western powers in colonizing Africa. Muhammad Ali's target: Sudan, which was gradually overrun by 1880. For a time, Sudan was run by Egyptian officials and their English and French fellow-travelers. Thus, if your ancestors were in Sudan in CE 1900, their ancestors could also have been in Egypt in CE 1800. Look to your family folklore.
Late nineteenth century - The cotton bubble: Egypt's period as a British colony came about as a debt foreclosure. The US civil war, by blocking access to North American cotton exports, had inflated the price of cotton - Egypt's major export . This cotton-bubble burst in 1865 when the Civil War ended. Financially overextended, Egypt agreed to British co-administration in 1879 and was, in effect, a British colony until 1944. The Mahdi rebellion in Sudan in 1891 enabled the British to extend their reach there, as well. Thus, if your ancestors were in Sudan or Egypt in CE 1900, their ancestors could also have been in Britain in CE 1800. Look to your family folklore.