84 A TROPICAL DEPENDENCY conditions would allow. I shall also hope to show that from any time of which history has note, the northern belt of the Soudan has been occupied by races of a higher than negroid type. The operation of these types upon the purely negroid races was to drive them southwards into the tropical swamps of the coast belt in which the higher type could not live.

The pressure of the tribes of the desert upon Negroland dates of course from a very much earlier period than the Arab conquest of North Africa, but it was renewed and accentuated by that conquest. The earliest Arab writer who is known to make any allusion to Arab dealings with Negroland in the west is Abd el Hakem, who died in Egypt in 870, but he merely alludes to a military expedition against the Berbers in the south-west, undertaken about the year 720, which reached the Soudan and brought back as much gold as the soldiers wanted. The next writer in point of date whose writings have been preserved is Ibn Haukal, the geographer, who wrote about the year 930. But he confines his writings chiefly to " those lands which are the seat of Islam and the residence of true believers," and though these extended in the tenth century from Spain to China, through Trans-Oxiana, Tibet, and Hindostan, the black countries of the Western Soudan are regarded as being still at that date outside the pale. " As for the Land of Blacks in West Africa," he says, '* I make but slight mention of them, because naturally loving wisdom, ingenuity, religion, justice, and regular government, how could I notice such people as those or exalt them by inserting an account of their countries." It is evident that this haughty writer had but a small acquaintance with the Land of the Blacks which he despises, and that he knew only its northern edge. "The Land of the Blacks," he says, **is a very extensive region, but extremely dry. In the mountains of it are to be found all the fruits which the Mohammedan world produces." He tells us also that it extends to the ocean on the south and Is bordered on the north by