Persian Gulf flooding of the basin started 15,000 years ago due to rising sea levels of the Holocene glacial retreat. This inland sea of some is connected to the Gulf of Oman in the east by the Strait of Hormuz; and its western end is marked by the major river delta of the Shatt al-Arab, which carries the waters of the Euphrates and the Tigris. In Iran this is called "Arvand Rood", where "Rood" means "river". Its length is , with Iran covering most of the northern coast and Saudi Arabia most of the southern coast. The Persian Gulf is about wide
Persian Gulf fall of Achaemenid Empire, and after the fall of the Parthian Empire, the Sassanid empire ruled the northern half and at times the southern half of the Persian Gulf. The Persian Gulf, along with the Silk Road, were important trade routes in the Sassanid empire. Many of the trading ports of the Persian empires were located in or around Persian Gulf. Siraf, an ancient Sassanid port that was located on the northern shore of the gulf, located in what is now the Iranian province of Bushehr, is an example of such commercial port. Siraf, was also significant in that it