Under these conditions the old tribal organisations were in great measure dissolved, and throughout its historic period of about a millennium Central Sudan is found mainly occupied by peoples gathered together in a small number of political systems, each with its own language and special institutions, but all alike accepting Islam as the State religion. Such are or were the Songhai empire, the Hausa States, and the kingdoms of Bornu with Kanem and Baghirmi, and these jointly cover the whole of Central Sudan as above defined. _Songhais_[171]. How completely the tribe[172] has merged in the people[172] may be inferred from the mere statement that, although no longer an independent nation[172], the negroid Songhais form a single ethnical group of about two million souls, all of one speech and one religion, and all distinguished by somewhat uniform physical and mental characters. This territory lies mainly about the borderlands between Sudan and the Sahara, stretching from Timbuktu east to the Asben oasis and along both banks of the Niger from Lake Debo round to the Sokoto confluence, and also at some points reaching as far as the Hombori hills within the great bend of the Niger. Here they are found in the closest connection with the Ireghenaten ("mixed") Tuaregs, and elsewhere with other Tuaregs, and with Arabs, Fulahs or Hausas[173], so that exclusively Songhai communities are now somewhat rare. But the bulk of the race is still concentrated in Gurma and in the district between Gobo and Timbuktu, the two chief cities of the old Songhai empire. They are a distinctly negroid people, presenting various shades of intermixture with the surrounding Hamites and Semites, but generally of a very deep brown or blackish colour, with somewhat regular features and that peculiar long, black, and ringletty hair, which is so characteristic of Negro and Caucasic blends, as seen amongst the Trarsas and Braknas of the Senegal, the Bejas, Danakils, and many Abyssinians of the region between the Nile and the Red Sea. Barth, to whom we still owe the best account of this historical people, describes them as of a dull, morose temperament, the most unfriendly and churlish of all the peoples visited by him in Negroland.