Persian Gulf is a crescent-shape groove which has demonstrated the encroachment of the Indian Ocean waters (Gulf of Oman) in an span of 900 km long and 240 km wide in the inferior folds of southern Zagros mountains. The Persian Gulf and its neighboring countries constitute almost one ninth of the 44 million square km span of the Asian continent. The Persian Gulf has been a valuable waterway since the beginning of history and as the venue of the collision of great civilizations of the ancient east, it has a background of several millenniums.