Ancient Aethiopia, (; also known as Ethiopia) first appears as a geographical term in classical documents in reference to the upper Nile region of Sudan, as well as certain areas south of the Sahara. Its earliest mention is in the works of Homer: twice in the Iliad, and three times in the Odyssey. The Greek historian Herodotus "specifically" uses the appellation to refer to such parts of sub-Saharan Africa as were then known within the inhabitable world. In classical antiquity, Africa (or 'Ancient Libya') specifically referred to what is now known as the Maghreb and south of the Libyan Desert and Western Sahara, including all the desert land west of the southern Nile river in North Africa, and not to Sub-Saharan Africa. Geographical knowledge of the continent gradually grew, with the Greek travelogue Periplus of the Erythraean Sea (1st century AD) describing areas along the Red Sea (Erythraean Sea). Etymology The Greek name Aithiopia (, from ) is a compound derived of two Greek words: + . According to the Perseus Project, this designation properly translates in noun form as burnt-face and in adjectival form as red-brown. As such, it was used as a vague term for dark-skinned populations since the time of Homer. The term was applied to such peoples when within the range of observation of the ancient geographers, primarily in what was then Nubia (in ancient Sudan). With the expansion of geographical knowledge, the exonym successively extended to certain other areas below the Sahara. Before Herodotus Homer () is the first to mention "Aethiopians" (, ), writing that they are to be found at the east and west extremities of the world, divided by the sea into "eastern" (at the sunrise) and "western" (at the sunset). In Book 1 of the Iliad, Thetis visits Olympus to meet Zeus, but the meeting is postponed, as Zeus and other gods are absent, visiting the land of the Aethiopians. And in Book 1 of the Odyssey, Athena convinces Zeus to let Odysseus finally return home only because Poseidon is away in Aithiopia and unable to object. Hesiod () speaks of Memnon as the "king of the Ethiopians." In 515 BC, Scylax of Caryanda, on orders from Darius I of the Achaemenid Empire, sailed along the Indus River, Indian Ocean, and Red Sea, circumnavigating the Arabian Peninsula. He mentioned "Aethiopians", though his writings on them have not survived. Hecataeus of Miletus