Although the negroes are the more numerous, the Arabs exceed in power. The bravery of the aboriginals is outweighed by the intelligence of the invaders and their superior force of character. During the second century of the Mohammedan era, when the inhabitants of Arabia went forth to conquer the world, one adventurous army struck south. The first pioneers were followed at intervals by continual immigrations of Arabs not only from Arabia but also across the deserts from Egypt and Marocco. The element thus introduced has spread and is spreading throughout the Soudan, as water soaks into a dry sponge. The aboriginals absorbed the invaders they could not repel. The stronger race imposed its customs and language on the negroes. The vigour of their blood sensibly altered the facial appearance of the Soudanese. For more than a thousand years the influence of Mohammedanism, which appears to possess a strange fascination for negroid races, has been permeating the Soudan, and, although ignorance and natural obstacles impede the progress of new ideas, the whole of the black race is gradually adopting the new religion and developing Arab characteristics. In the districts of the north, where the original invaders settled, the evolution is complete, and the Arabs of the Soudan are a race formed by the interbreeding of negro and Arab, and yet distinct from both. In the more remote and inaccessible regions which lie to the south and west the negro race remains as yet unchanged by the Arab influence. And between these extremes every degree of mixture is to be found. In some tribes pure Arabic is spoken, and prior to the rise of the Mahdi the orthodox Moslem faith was practised. In others Arabic has merely modified the ancient dialects, and the Mohammedan religion has been adapted to the older superstitions; but although the gap between the Arab-negro and the negro-pure is thus filled by every intermediate blend, the two races were at an early date quite distinct. The qualities of mongrels are rarely admirable, and the mixture of the Arab and negro types has produced a debased and cruel breed, more shocking because they are more intelligent than the primitive savages. The stronger race soon began to prey upon the simple aboriginals; some of the Arab tribes were camel-breeders; some were goat-herds; some were Baggaras or cow-herds. But all, without exception, were hunters of men. To the great slave-market at Jedda a continual stream of negro captives has flowed for hundreds of years. The invention of gunpowder and the adoption by the Arabs of firearms facilitated the traffic by placing the ignorant negroes at a further disadvantage. Thus the situation in the Soudan for several centuries may be summed up as follows: The dominant race of Arab invaders was unceasingly spreading its blood, religion, customs, and language among the black aboriginal population, and at the same time it harried and enslaved them.