In commenting on the religion[1377] of the Saracens the medieval Christians made the fundamental error of supposing that Islam is an idolatrous cult and that Mohammed was worshipped as a god. Nevertheless they were far from inaccurate in their remarks on the various customs, habits, and minor beliefs of the Moslems, on such matters, for example, as the pilgrimage to Mecca, the prohibited eating of pork and drinking of wine, the importance of ablutions, polygamy, and the customs of divorce. William of Tyre describes[1378] the division of the Mohammedans into two great groups, Shiah and Sunni, and explains how the former held that Ali (“Haly”) was the only true prophet and the latter that Mohammed was the one messenger of God. Baghdad was referred to as the seat of the great “apostle” of the Saracens, or caliph, whom William of Tyre spoke of as a sovereign prince and chieftain whom all must obey; Cairo in Egypt was recognized as the capital of the caliphs of the rival Shiah persuasion. Benjamin of Tudela also acquired some fairly clear ideas of Islam during his visits to Baghdad and to Egypt. He states that the Abbasid Caliph at Baghdad “is head of the Mohammedan religion, and all the kings of Islam obey him” and likens his position to that of the Christian Pope.[1379] In writing about Cairo he tells us that the subjects of the Emir were followers of Ali (hence Shiites), that they rose against the Abbasid Caliph of Baghdad, and that a lasting feud was kept up between the two factions.[1380] Particular terror was inspired in the hearts of the Crusaders by that strange sect of Assassins,[1381] whose principal seat was at Alamut in Persia, the stronghold of the notorious Old Man of the Mountain, though most of the Crusaders mistakenly thought that the outlying fortress of Massiat in Syria was the abode of the Old Man. William of Tyre dilates[1382] on the treachery and murderous nature of this people; and in Ambroise’s _Estoire_ we find[1383] a vivid account of how the children of the Assassins were brought up to do the bidding of the Old Man in every detail and in particular to bring about the murder of his enemies.[1384] _AFRICA_ EGYPT AS PART OF ASIA Both the author of the _De imagine mundi_ and Gervase of Tilbury include an account of Egypt with their descriptions of the countries of Asia. They then take up the remainder of Asia and Europe before finally returning to Africa toward the close of the geographical parts of their books. This order of treatment, which accorded with classical traditions, usually included Egypt with Asia or at least, as in the _De imagine mundi_, made the Nile rather than the Red Sea the boundary between Asia and Africa.[1385] Certainly from an historical and cultural point of view Egypt has been more closely related to the Asiatic than to the African continent, even though geographically it forms a portion of the latter.[1386]