In 550 BC, the Achaemenid Empire established the first Persian Empire in Pars (Persis, or modern Fars) in the southwestern region of the Iranian plateau. Consequently in the Greek sources, the body of water that bordered this province came to be known as the Persian Gulf.
Considering the historical background of the name Persian Gulf, Sir Arnold Wilson mentions in a book, published in 1928 that:
“ No water channel has been so significant as Persian Gulf to the geologists, archaeologists, geographers, merchants, politicians, excursionists, and scholars whether in past or in present. This water channel which separates the Iran Plateau from the Arabia Plate, has enjoyed an Iranian Identity since at least 2200 years ago. ”
No written record has remained from the era before the Persian Empire, but in the oral history and culture, the Iranians have called the southern waters: "Jam Sea", "Iran Sea", and "Pars Sea".
During the years 550 to 330 BC, coinciding with the sovereignty of the first Persian Empire over the Middle East area, especially the whole part of the Persian Gulf and some parts of the Arabian Peninsula, the name of "Pars Sea" is widely found in the compiled written texts.
In the travel account of Pythagoras, several chapters are related to description of his travels accompanied by Darius the Great, to Susa and Persepolis, and the area is described. From among the writings of others in the same period, there is the inscription and engraving of Darius the great, installed at junction of waters of Red Sea (also called "Arabian Gulf" or "Ahmar Sea") and the Nile river and the Rome river (current Mediterranean) which belongs to the 5th century BC where, Darius the Great, the king of the Achaemenid Empire has named the Persian Gulf Water Channel: Pars Sea (Persian Sea).