The colonization of Africa in all its earlier stages is so closely akin to exploration, that in several of the preceding chapters I have seemed to deal rather with geographical discoveries than with political settlement. But as there is much exploring work which has not been directly connected with colonization (just as all missionary work has not resulted in the foundation of European states in Africa, nor have measures for the suppression of the slave trade invariably been followed by annexation) I think it better to devote a chapter to the enumeration of great explorers whose work has proved to be an indirect cause of the ultimate European control now established over nearly all Africa. The first explorers known to history, though not, unfortunately, mentioned by name, were those Phoenicians despatched by the Egyptian Pharaoh, Niku II (son of Psammetik), about 600 (603-599) B.C. to circumnavigate Africa. We receive our knowledge of them through Herodotos, who derived his information from Egypt; but the account given of the voyage bears the stamp of veracity and probability, and seemed to be confirmed by some remarkable inscriptions on scarabs discovered by French explorers of Egyptian monuments. These, however, have been declared to be forgeries[163]. Cambyses, the Persian king who invaded Egypt in 525 B.C., is said to have lost his life in endeavouring to trace the course of the Nile, he and his army having disappeared in the deserts of Upper Nubia. About 520 B.C. Hanno the Carthaginian, as already related in Chapter II, conducted an expedition round the West coast of Africa, which penetrated about as far south as the confines of Liberia. The Greek Herodotos journeyed in Egypt and in the Cyrenaica about 450 B.C. Eratosthenes, a Greek, born at Kurene in 276 B.C., became the librarian of one of the Ptolemies at Alexandria, and, although he derived much of his information about the valley of the Nile from other travellers, still he conducted a certain amount of exploration himself. Polybius, a Greek, born in 204 B.C., explored much of the North coast of Africa in the service of the Romans about 140 years before the Christian Era. The celebrated Strabo flourished during the reign of Augustus Cæsar, and wrote a great work on geography about the year 19 A.C. He accompanied the Roman governor Ælius Gallus on a journey up the Nile as far as Philæ, though his knowledge of the Cyrenaica was limited to a voyage along the coast. Nero sent two centurions (according to Pliny) with orders to ascend the Nile and discover its course. Thanks to recommendations from the king of Ethiopia, they were passed on from tribe to tribe, and apparently ascended the Nile as far as its junction with the Sobat, where they were stopped by immense masses of floating vegetation (the _sudd_).