A very brilliant feature on the maps of our period is the Red Sea, almost invariably colored red. This name was given to the entire Indian Ocean, and the red color was applied to the Persian Gulf as well as to the “Arabian Gulf,” or Red Sea proper. The name “Indian Ocean” was also occasionally used, as, for example, on the Jerome map of the East.[1305] The Greeks had acquired some fairly correct information about the northwestern shores of the Indian Ocean and had heard vague rumors of the great peninsula and islands east and south of India: Malaya, Ceylon, Sumatra. Confused reports of the geography of Taprobane, or Ceylon, are found in classical works as far back as the time of the expedition of Alexander. Pliny, Solinus, Ptolemy, and others described Taprobane in some detail but exaggerated its dimensions to enormous proportions. Pomponius Mela had spoken of the islands of Chryse, lying off the eastern promontory of Asia, and Argyre, off the mouth of the Ganges. Perhaps these represented some vague knowledge of the Andamans or Nicobars or the Malay Peninsula; and certainly we recognize the last-named in the Aurea Chersonesus of Ptolemy. _Islands of the Indian Ocean_ Some relics of this classical knowledge of Indian seas and isles was retained in the Middle Ages. Isidore[1306] had spoken of “Chrisa” and “Argare” as full of gold and silver and perpetually blooming flowers, with mountains of gold guarded by dragons and griffons. This account found its way into the _De imagine mundi_[1307] and was copied by Gervase of Tilbury;[1308] the islands themselves, together with the “Island of the Sun” of Pliny, Mela, Solinus, and others, figured on many contemporary maps.[1309] Orosius had said that in Taprobane there were ten cities.[1310] Isidore, whom Gervase of Tilbury copied, added that the dimensions of the island were 875 by 625 miles, that it has two summers and two winters each year, and that the vegetation always remains green.[1311] Solinus had described[1312] Taprobane as being divided in two by a river; one half, he said, was full of wild beasts, but the other was inhabited by men. This division of the island is perpetuated on the Henry of Mayence,[1313] Jerome,[1314] Hereford,[1315] and Ebstorf maps.[1316] _Al-Battānī on the Indian Ocean_