[Footnote 83: By one Ibn Fatimah, who was wrecked at Wad-Nun, a little North of Cape Non, put off in a sloop with some sailors, and at last came to a glittering white headland, from which they were warned off by some Berbers. They learned afterwards that it was one mass of deadly serpents. Thence turning North they landed and went inland to the salt market of Tagazza, and finally returned home.] This last point is one which requires special consideration. By sea the Arabs did scarcely anything to prepare the way for the Christian discoveries of the fifteenth century in Africa (except along the Eastern coast), but by land they were the most important helpers and informants of Prince Henry.[84] Islam effected the conquest of the Barbary States, politically in the seventh century, dogmatically in the course of about 200 years after the days of Tarik and Musa. By the end of the eleventh century the faith of Mohammed had begun to spread and take deep root in the Sudan,[85] having already made its way into many parts of the Sahara. With the Moslem faith came the Moslem civilisation. The caravan trade across the desert now commenced between Negroland and the Mediterranean; "Timbuktu" was founded by Moslems, probably drawn in large measure from the Tuareg, in about 1077-1100; and the Central Sudan States, from Sokoto to Darfur and Kordofan, passed under Mohammedan influence between A.D. 1000 and 1250. With the fresh migration of Nomad Arabs which seems to have taken place about A.D. 1050, from Upper Egypt to West Africa, a distinct advance of Islam in Central Africa is to be noticed by way of Kanem, Bornu, Sokoto, and the Niger Valley; this new wave reached Jenné, Ghiné, or "Guinea", on the Upper Valley of the Niger. [Footnote 84: Cf. what is said about Prince Henry's correspondent, the merchant at Oran, p. xxvi of this Introduction.]