In the third century before Christ, Egypt passed under the rule of the Ptolemies. Ptolemy Philadelphus (B.C. 250-247), a man of wide outlook, built Arsinoë (north-east of the later Suez) to serve as a port in place of the ancient Heroöpolis, which was silting up. He further sent out an expedition to explore the coasts of the Red Sea under the charge of Ariston. Diodorus Siculus (_c._ B.C. 20), quoting Agatharcides (B.C. 110), and the geographer Strabo (_c._ A.D. 24), quoting Artemidorus (B.C. 100), give an account of the information that is preserved regarding Sinai. After describing the western shore of the Red Sea with its countries and its inhabitants who were Ichthyophagoi (fish-eaters), and Troglodytes (cave-dwellers) or nomads, and the dangers which threatened shipping from storms and sand-banks, Diodorus, in his account, passed to the other side of the Gulf. Here Ariston erected an altar at Neptunium or Posidium. “From thence to the mouth of the Gulf, is a place along the sea-coast of great esteem among the inhabitants for the profit it yields them; it is called the Garden of Palm-trees (Phoenikon), because they abound there, and are so very fruitful that they yield sufficient both for pleasure and necessity. But the whole country next adjoining is destitute of rivers and brooks, and lying to the south is even burned up by the heat of the sun; and therefore this fruitful tract that lies amongst dry and barren regions (remote from tillage and improvement), and yet affords such plenty of food and provision, is justly, by the barbarians, dedicated to the gods. For there are in it many fountains and running streams as cold as snow, by which means the region from one side to the other is always green and flourishing, and very sweet and pleasant to the view. In this place there is an ancient altar of hard stone, with an inscription in old and illegible characters; where a man and a woman, that execute here the priest’s office during their lives, have the charge of the grove and altar. They are persons of quality and great men that abide here, and for fear of the beasts, have their beds (they rest upon) in the trees.”[118] In the corresponding account Strabo mentioned no altar, but the man and woman who guarded the trees.[119] The Phoenikon or palm grove of these writers, was sometimes located at Raithou; perhaps the one at Ayun Musa is meant.