Not long after the Romans had annexed Egypt to their Empire, they had begun to push their control of the Nile beyond the First to the Second Cataract. Ahead of them went Greek explorers, mainly from Kurene or Asia Minor, who traced the Nile upstream about as far as Khartum, perhaps even beyond. All this region beyond the Second Cataract was known either as the Nubian Kingdom of Napata (which was then peopled by Ethiopians speaking Hamitic languages) or as Meroe (Merawi). The term Meroe applied not only to a city but also to the supposed island, a considerable tract of land nearly enclosed by the courses and tributaries of the Blue Nile, White Nile, and Atbara, a region formerly of great fertility which played a considerable part in the civilizing of Inner Africa, especially westwards towards Lake Chad. The Emperor Nero was temporarily interested in the mystery of the Nile sources and despatched an expedition under two centurions about the year 66 A.C., to discover the origin of the White Nile. This Roman expedition was organized in the principality of Meroe and furnished with boats and men by the Nubian or the Ethiopian chiefs. These boats were subsequently exchanged higher up the Nile for dug-out canoes; and in these the two centurions apparently travelled as far south as the confluence of the Bahr-el-Ghazal and the Kir or White Nile. Their further explorations seem to have been stopped by the accumulation of water vegetation called the sudd. Discouraged by the natural obstacles to their penetration of this desolate region, by the hostility of the naked Nile negroes, and no doubt also by the unendurable attacks of the mosquitoes, the two centurions returned to Egypt; and their discouraging reports apparently put an end to further Roman enterprise in this direction.