Yet since some remote if undated epoch the specialised Negro type, as depicted on the Egyptian monuments some thousands of years ago[135], has everywhere been maintained with striking uniformity. "Within this wide domain of the black Negro there is a remarkably general similarity of type.... If you took a Negro from the Gold Coast of West Africa and passed him off amongst a number of Nyasa natives, and if he were not remarkably distinguished from them by dress or tribal marks, it would not be easy to pick him out[136]." Nevertheless considerable differences are perceptible to the practised eye, and the contrasts are sufficiently marked to justify ethnologists in treating the _Sudanese_ and the _Bantu_ as two distinct subdivisions of the family. In both groups the relatively full-blood natives are everywhere very much alike, and the contrasts are presented chiefly amongst the mixed or Negroid populations. In Sudan the disturbing elements are both Hamitic (Berbers and Tuaregs) and Semitic (Arabs); while in Bantuland they are mainly Hamitic (Galla) in all the central and southern districts, and Arabs on the eastern seaboard from the equator to Sofala beyond the Zambesi. To the varying proportions of these several ingredients may perhaps be traced the often very marked differences observable on the one hand between such Sudanese peoples as the Wolof, Mandingans, Hausa, Nubians, Zandeh[137], and Mangbattu, and on the other between all these and the Swahili, Baganda, Zulu-Xosa, Be-Chuana, Ova-Herero and some other Negroid Bantu. But the distinction is based on social, linguistic, and cultural, as well as on physical grounds, so that, as at present constituted, the Sudanese and Bantu really constitute two tolerably well-defined branches of the Negro family. Thanks to Muhammadan influences, the former have attained a much higher level of culture. They cultivate not only the alimentary but also the economic plants, such as cotton and indigo; they build stone dwellings, walled towns, substantial mosques and minarets; they have founded powerful states, such as those of the Hausa and Songhai, of Ghana and Bornu, with written records going back a thousand years, although these historical peoples are all without exception half-breeds, often with more Semitic and Hamitic than Negro blood in their veins.