In the sixth century the Nubians were converted to Christianity by a
Byzantine priest, and they immediately began to develop. A new capital,
Dongola, replaced Nepata and Meroe, and by the twelfth century churches
and brick dwellings had appeared. As the Mohammedan flood pressed up the
Nile valley it was the Nubians that held it back for two centuries.

Farther south other wild tribes pushed out of the Sudan and began a
similar development. Chief among these were the Fung, who fixed their
capital at Senaar, at the junction of the White and Blue Nile. When the
Mohammedan flood finally passed over Nubia, the Fung diverted it by
declaring themselves Moslems. This left the Fung as the dominant power in
the fifteenth century from the Three Cataracts to Fazogli and from the Red
Sea at Suakin to the White Nile. Islam then swept on south in a great
circle, skirted the Great Lakes, and then curled back to Somaliland,
completely isolating Abyssinia.

Between the thirteenth and sixteenth centuries the Egyptian Sudan became a
congeries of Mohammedan kingdoms with Arab, mulatto, and Negro kings. Far
to the west, near Lake Chad, arose in 1520 the sultanate of Baghirmi,
which reached its highest power in the seventh century. This dynasty was
overthrown by the Negroid Mabas, who established Wadai to the eastward
about 1640. South of Wadai lay the heathen and cannibals of the Congo
valley, against which Islam never prevailed. East of Wadai and nearer the
Nile lay the kindred state of Darfur, a Nubian nation whose sultans
reigned over two hundred years and which reached great prosperity in the
early seventeenth century under Soliman Solon.

Before the Mohammedan power reached Abyssinia the Portuguese pioneers had
entered the country from the east and begun to open the country again to
European knowledge. Without doubt, in the centuries of silence, a