Isius Mons
τὸ Ἴσιον ὄρος
Isius Mons (τὸ Ἴσιον ὄρος, Ptol. 4.7.5), a mountain, or rather a ridge of highlands rising gradually on its western side, but steep and escarped towards the east, on the coast of Aethiopia, and in the Regio Troglodytica. It was seated in lat. 20° 1‘ N., a little to the southward of the headland Mnemium (Μνημεῖον ἄκρον, Ptol. 4.5.7), and SW. of Berenice and the Sinus Immundus (Foul Bay). Mons Isius answers to the modern Ras-el-Dwaer. Strabo, indeed (xvii. p. 770), places this eminence further to the south, and says that it was so called from a temple of Isis near its summit.
From William Smith (ed.), Dictionary of Greek and Roman Geography. Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities and Tufts University. Data accessed from https://github.com/PerseusDL/canonical-pdlrefwk/ on 17 October 2026.