First state consisting all of western Iran was founded by the Proto-Elamite with their capital at Susa & Anshan which lasted from around 3200 BC to 2700 BC and had a significant influence on later Iranian dynasties, they were followed by Elam (2700 BC-550 BC) and Indo-European Medes who created the first Iranian empire, which encompassed all of Iran and lasted from 728 to 550 BC, Cyrus The Great, founded the first Persian Empire, the Achaemenid Empire in 550 BC (the Achaemenid had ruled Anshan for about a century before that).
The Achaemenid conquered the neighboring Mesopotamian Civilization, and was the world's first super state, stretching from Greece to India. Persia was conquered by the Greeks under Alexander the Great, Arab Islamic Caliphate and the Mongol Empire with subsequent reunifications afterwards. The last reunification of Iran happened in 1501 by the Safavid dynasty. Iran was referred to in the West as Persia until March 21, 1935 when it was officially recognized as Iran which has been the local name. The modern Islamic Republic of Iran was established on February 11, 1979 after revolution toppled Pahlavi dynasty. Iran has had roughly the same geographical boundaries since its inception and has been using Persian as the official language in addition to Iranian calendar as official calendar as well as the name of Iran for the nation since Median Empire.
In the fifth century B.C., Darius the Great of the Achaemenid dynasty called the Persian Gulf "Draya; tya; haca; parsa: Aitiy", meaning, "The sea which goes from Persian". In this era, some of the Greek writers also called it "Persikonkaitas", meaning the Persian Gulf. Claudius Ptolemaues, the celebrated Greco-Egyptian mathematician/astronomer in the second century called it "Persicus Sinus" or Persian Gulf. In the first century A.D., Quintus Curticus Rufus, the Roman historian, designated it "Aquarius Persico" – the Persian Sea. Flavius Arrianus, another Greek historian, called it "Persikonkaitas" (Persian Gulf). During the Sassanian dynasty and the time of the Prophet Muhammad and the 4 caliphs, the name invariably used was the "Persian Sea". This was continued by the Ummayyads and Abbasids, while during the Ottomans used either "Persian Gulf" or "Persian Sea". At the Twenty-third session of the United Nations in March-April 2006, the name "Persian Gulf" was confirmed again as the legitimate and official term to be used by members of the United Nations.