132 THE PROGRESS THROUGH EGYPT ii. i. iii.

a section of Kenana, contained among others the Beni Makhzum, the Beni 'AbbAs, and the Beni Ommayya.

The ancient capital of the Kahtanite Arabs was at Sana'a in the Yemen, but a century or so after the Christian era large numbers of them migrated northwards in consequence, tradition has it, of the bursting of the great dam of Marib, and settled there.

Thus the Beni Lakhm came to found the Monadira dynasty at Hi'ra, near the ancient site of Babylon, and ruled the Arabs of 'Irak as vassals of Persia-.

The Ghassan took up their abode near Damascus and from about 37 to 636 a.d. maintained a control, under the aegis of the Byzantine emperors, over a considerable portion of Syria.

The Kuda'a group, particularly the Guhayna and Beli, settled in the northern half of the Hegaz having all but extirpated the ancient tribes of Thammud* and Ad, who had previously Hved there and who are likely to have been cognate to the Hamitic tribes inhabiting the opposite African coast .

IV Previously to Islam the difference between the Kahtanite and Isma'ilitic tribes had been to some extent accentuated by a difference of language, for the more southernly group spoke Himyaritic; but the tribal movements that took place in Arabia after the Christian era resulted in a spread of Arabic, and with the acceptation of Muhammadanism that language became completely paramount.

We shall see later that the distinction between Kahtanite and Isma'ilitic survives under a rather different guise in the Sudan at the present date.

V Let us now pass to the conquest of Egypt by the Arabs in the seventh century.

The profuseness of details we possess concerning the conquest is only equalled by their inconsistency. The chief reason for this is to be found in the fact that the earhest writers of all were Copts, who were chiefly concerned with matters of church history; and the records of the earliest Arab historians, between whom and the Copts there is, in any case, a sad gulf, are either lost or only partially extant in the extracts preserved by later writers.

Caussin de Perceval (i, 85-87) puts the bursting of the dam about 120 A.D., but shews that there is considerable divergence of opinion as to the exact date.

Abu el Fida, pp. 122 et seq. and Van Dyck, p-. 24.

Abu el Fida, pp. 128 et seq. and Van Dyck, pp. 28-31.

'' Diodorus's Thamudeni.

' Cp. Burton, Land of Midian, u, 220 et seq.; Sale, Prel. Disc.

* See Butler, Arab Conquest..., pp. vi-xxi. The difficulties are also increased by the inaccessibility of several important MSS. and the general scarcity of adequate translations.