The sea then makes a two-fold indentation[479] in the land upon these coasts, under the name of Rubrum[480] or “Red,” given to it by our countrymen; while the Greeks have called it Erythrum, from king Erythras,[481] or, according to some writers, from its red colour, which they think is produced by the reflection of the sun’s rays; others again are of opinion that it arises from the sand and the complexion of the soil, others from some peculiarity in the nature of the water. (24.) Be this as it may, this body of water is divided into two gulfs. The one which lies to the east is called the Persian Gulf, and is two thousand five hundred miles in circumference, according to Eratosthenes. Opposite to it lies Arabia, the length of which is fifteen hundred miles. On the other side again, Arabia is bounded by the Arabian Gulf. The sea as it enters this gulf is called the Azanian[482] Sea. The Persian Gulf, at the entrance, is only five[483] miles wide; some writers make it four. From the entrance to the very bottom of the gulf, in a straight line, has been ascertained to be nearly eleven hundred and twenty-five miles: in outline it strongly resembles[484] the human head. Onesicritus and Nearchus have stated in their works that from the river Indus to the Persian Gulf, and from thence to Babylon, situate in the marshes of the Euphrates, is a distance of seventeen hundred miles. In the angle of Carmania are the Chelonophagi,[485] who cover their cabins with the shells of turtles, and live upon their flesh; these people inhabit the next promontory that is seen after leaving the river Arbis;[486] with the exception of the head, they are covered all over with long hair, and are clothed in the skins of fishes. (25.) Beyond their district, in the direction of India, is said to be the desert island of Caicandrus, fifty miles out at sea; near to which, with a strait flowing between them, is Stoidis, celebrated for its valuable pearls. After passing the promontory[487] are the Armozei,[488] joining up to the Carmani; some writers, however, place between them the Arbii,[489] extending along the shore a distance of four hundred and twenty-one miles. Here is a place called Portus Macedonum,[490] and the Altars of Alexander, situate on a promontory, besides the rivers Saganos, Daras, and Salsa. Beyond the last river we come to the promontory of Themisteas, and the island of Aphrodisias, which is peopled. Here Persis begins, at the river Oratis,[491] which separates it from Elymais.[492] Opposite to the coast of Persis, are the islands of Psilos, Cassandra, and Aracia, the last sacred to Neptune,[493] and containing a mountain of great height. Persis[494] itself, looking towards the west, has a line of coast five hundred and fifty miles in length; it is a country opulent even to luxury, but has long since changed its name for that of “Parthia.”[495] I shall now devote a few words to the Parthian empire. CHAP. 29.—THE PARTHIAN EMPIRE.