The most complete and accurate summing up of the regional geography of the ancients was the _Geography_ of Strabo, written in Greek probably shortly before 17 A. D. But, as we have seen, this work was unknown to our period of the Middle Ages, when men had to rely on Latin writers like Pomponius Mela and Pliny, whose writings were of distinctly inferior quality and included a great deal of fabulous and worthless material. Devoid of that critical judgment which characterized Eratosthenes and Strabo, Mela and Pliny were content to bring together huge quantities of miscellaneous information, much of which was derived from antiquated Greek sources. Mela, for example, closely follows Herodotus’ description of the marvels of Asia, and Pliny retails many of the fanciful legends of Ctesias and Megasthenes. Pliny’s contributions to geography were somewhat more satisfactory than those of Mela; for he added some details about Asia that had not been mentioned before, especially in his description of Serica and of India and in his account of the monsoons. On the other hand Mela was the first writer to mention the Baltic Sea, or “Sinus Codanus,” which he described as a great gulf full of islands. THE “PERIPLUS OF THE ERYTHRAEAN SEA” Nearly contemporaneously with Pliny there came an advance in the knowledge of the Indian Ocean in the anonymous Greek _Periplus of the Erythraean Sea_, a manual for sailors and merchants. This is of interest because it gave indications of the existence of coasts and islands beyond India, the islands of Chryse, the land of the Seres, and, at the end of the earth to the east, a region of “Thin”—the first mention of the word “China” in the West unless we take into account the “Sinim” of Isaiah xlix, 12, which may or may not have referred to the great nation of the Far East. At about the same time, as we have already seen, the upper reaches of the Nile, possibly as far as the great marshes of the White Nile in about latitude 9° N., were explored by the expedition described by Seneca and Pliny which Nero sent out to solve the age-long mystery’ of the sources of the river of Egypt.[172] Pliny accordingly placed the southern border of the _oikoumene_ some 7½° south of the position to which Eratosthenes had assigned it, or at about latitude 4° N.[173] LIMITS OF ANCIENT REGIONAL KNOWLEDGE ON THE SOUTH AND EAST