Persian Gulf as "The Northwestern limit of Gulf of Oman". This limit is defined as "A line joining Ràs Limah (25°57'N) on the coast of Arabia and Ràs al Kuh (25°48'N) on the coast of Iran (Persia)". The gulf is connected to Indian Ocean through Strait of Hormuz. Writing the water balance budget for the Persian Gulf, the inputs are river discharges from Iran and Iraq (estimated to be 2000 cubic meters per second), as well as precipitation over the sea which is around 180mm/year in Qeshm Island. The evaporation of the sea is high, so that after considering river discharge and
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