From the earliest period of Muslim history North Africa has been the favourite field of exploitation of every sect and political party which found itself in opposition to the official Khalifate, and there has always been very close intercourse between that area and South Arabia; indeed, there are even common peculiarities of dialect between the two. Thus we find that as soon as the new Ismaʿilian sect was established in Yemen, Ibn Hawshab sent two missionaries, Hulwani and Abu Sufyan (Maq. ii. 10) to preach in the province of Ifrikiya, the modern Tripoli and Tunis, where their work seems to have lain particularly amongst the aboriginal Berber population, for the Berbers were always more disposed to any heresy or rebellion which would give them a good pretext for making war against the ruling Arabs. Nothing is known of the subsequent history of these two missionaries save that after a brief career during which they seem to have made a deep impression, especially on the Katama tribe, they died. This Katama tribe lived in the broken territory north-west of the town of Constantine, in what would now be north-east Algeria. As we shall have to refer more than once to the geography of North Africa it will be convenient here to make a brief statement of its political divisions and condition in the fourth century A.H. By North Africa we understand the whole territory lying between the land of Egypt on the east and the Atlantic on the west, bounded by the Mediterranean on the north and by the great desert on the south. Previous to the Arab invasion this land was inhabited by the Berbers or Libyans, the same who, under the name of _Lebu_, had constantly threatened Egypt in the days of the Pharaohs. As a race these Berbers seem to have progressed little since neo-lithic times, and were still in the condition of nomadic tribes like the Arabs of the pre-Islamic period. Their language was not Semitic, but it has many very marked Semitic affinities and, although language transmission is often quite distinct from racial descent, it seems quite probable that in this case the race bore a parallel relation to the Arab stock. This would be best explained by the supposition that both were derived from a neo-lithic race, which at one time spread along the whole of the southern coast of the Mediterranean and across into Western Asia, but that some cause, perhaps the early development of civilization in the Nile valley, had cut off the eastern wing from the rest, and this segregated portion developed the distinctive characteristics which we term Semitic.