The Erythraean Sea (Ancient Greek: Ἐρυθρὰ Θάλασσα, Erythrà Thálassa, lit. 'Red Sea') was a former maritime designation that always included the Gulf of Aden, and at times other seas between Arabia Felix and the Horn of Africa. Originally an ancient Greek geographical designation, the term was used throughout Europe until the 18th and 19th centuries. The area referred to by this name frequently extended beyond the Gulf of Aden—as in the famous 1st-century Periplus of the Erythraean Sea—to designate all of the present-day Red Sea, Arabian Sea, Persian Gulf, and Indian Ocean as a single maritime area.
In ancient Greek geography the basin of the Indus River was on the extreme eastern fringe of the known world. The term "India" (Indikē in Greek) was used by Herodotus and later Greek writers in three different senses: the Achaemenid Persian province Hindush which was at the lower Indus basin (Sindh), the entire Indus land, which contained two other Persian provinces—Thatagush and Gandāra, and the whole of Indian subcontinent. The ethnic term "Indians" (Indoi) was most often used for Indians in the modern sense, represented by physical appearance and cultural markers such as wearing cotton, driving chariots and carrying iron-tipped arrows.