The residence of this Arab prince, called for shortness Wed Ageeb, was at Gerri, a town in the very limits of the tropical rains, immediately upon the ferry which leads across the Nile to the desert of Bahiouda, and the road to Dongola and Egypt, joining the great desert of Selima. This was a very well-chosen situation, it being a toll-gate, as it were, to catch all the Arabs that had flocks, who, living within the rains in the country which was all of fat earth, were every year, about the month of May, obliged by the fly to pass, as it were, in review, to take up their abode in the sandy desert without the tropical rains. By the time fair weather returned in the fertile part of the country to the southward, and freed them from the fly, all sorts of verdure had grown up in great luxuriancy, while hunger stared them now in the face among the sands to the northward, where every thing eatable had been consumed by the multitudes of cattle that had taken refuge there. The Arab chief, with a large army of light, unincumbered horse, stood in the way of their return to their pastures, till they had paid the uttermost farthing of tribute, including arrears, if any there were. Such was the state and government of the whole of this vast country, from the frontiers of Egypt to those of Abyssinia, at the beginning of the 16th century. In the year 1504, a black nation, hitherto unknown, inhabiting the western banks of the Bahar el Abiad, in about latitude 13°, made a descent, in a multitude of canoes, or boats, upon the Arab provinces, and in a battle near Herbagi, they defeated Wed Ageeb, and forced him to a capitulation, by which the Arabs were to pay to their conquerors, in the beginning, one half of their stock, and every subsequent year, one-half of the increase, which was to be levied at the time of their passing into the sands to avoid the fly. Upon this condition, the Arabs were to enjoy their former possessions unmolested, and Wed Ageeb his place and dignity, that he always might be ready to use coercion in favour of the conquerors, in case any of the distant Arabs refused payment, and he thus became as it were their lieutenant.