224 A TROPICAL DEPENDENCY coast. The Empire of Bornu, or Kanem, including at one time the present kingdoms of Wadai and Darfour, formed a separation between these two streams which have always run in parallel channels from south to north. This, at least, is the general opinion of explorers and historians, who, it is to be remembered, have necessarily written from the external point of view. What may have been at any given period the lateral branching of local native trade, is difficult for the European writer to determine.

Heeren, in his researches into the trade of the Carthaginians and the Ethiopians, has been able to establish the existence of at least one important cross-road of communication, of which a portion has been already noted in tracing the direction of the main trade route, after it branched from Thebes westward to the oasis of Siwah and the Mediterranean coast. The western end of the road starting from Carthage ran in a south-easterly direction through the Fezzan to the site of the present Murzuk. After making the junction at that point with the Egyptian road, it turned southwards to the Niger, and was the road which has been so often mentioned as the Tripoli-Fezzan road of the present day. Along this road the Carthaginians traded with the Niger for carbuncles, skins, gold, ivory, and other goods.

Thus we get on unquestionable authority evidence of a well-established connection in very early times between Ethiopia and Egypt by the Valley of the Nile ; between Egypt and Carthage by a road crossing the desert through Siwah and Augela, and between Carthage and the Niger by the present Tripoli- Fezzan route. If we take Murzuk and Thebes as lying almost on the same parallels of latitude outside the Tropic of Cancer, and Gao and Meroe as having also almost parallel positions on the edge of the summer rains, some eight degrees farther south, we get the four corners of an irregular parallelogram, of which three sides were in permanent communication with each other. The base of this parallelogram rests on the fertile belt, which crosses Africa