The Persian Gulf is a mediterranean sea in Western Asia. The body of water is an extension of the Indian Ocean (Gulf of Oman) through the Strait of Hormuz and lies between Iran to the northeast and the Arabian Peninsula to the southwest. The Shatt al-Arab river delta forms the northwest shoreline.

The Persian Gulf was a battlefield of the 1980–1988 Iran–Iraq War, in which each side attacked the other’s oil tankers. It is the namesake of the 1991 Gulf War, the large air- and land-based conflict that followed Iraq’s invasion of Kuwait.

The gulf has many fishing grounds, extensive coral reefs, and abundant pearl oysters, but its ecology has been damaged by industrialization and oil spills.

The body of water is historically and internationally known as the “Persian Gulf”. Some Arab governments refer to it as the “Arabian Gulf” or “The Gulf”, but neither term is recognized internationally. The name “Gulf of Iran (Persian Gulf)” is used by the International Hydrographic Organization.

The Persian Gulf is geologically very young, having been formed around 15,000 years ago

The world’s oldest known civilization (Sumer) developed along the Persian Gulf and southern Mesopotamia. The shallow basin that now underlies the Gulf was an extensive region of river valley and wetlands during the transition between the end of the Last Glacial Maximum and the start of the Holocene, which, according to University of Birmingham archaeologist Jeffrey Rose, served as an environmental refuge for early humans during periodic hyperarid climate oscillations, laying the foundations for the legend of Dilmun.

For most of the early history of the settlements in the Persian Gulf, the southern shores were ruled by a series of nomadic tribes. During the end of the fourth millennium BC, the southern part of the Persian Gulf was dominated by the Dilmun civilization. For a long time, the most important settlement on the southern coast of the Persian Gulf was Gerrha. In the 2nd century the Lakhum tribe, who lived in what is now Yemen, migrated north and founded the Lakhmid Kingdom along the southern coast. Occasional ancient battles took place along the Persian Gulf coastlines, between the Sassanid Persian empire and the Lakhmid Kingdom, the most prominent of which was the invasion led by Shapur II against the Lakhmids, leading to Lakhmids’ defeat, and advancement into Arabia, along with the southern shore lines. During the 7th century, the Sassanid Persian empire conquered the whole of the Persian Gulf, including southern and northern shores.

Between 625 BC and 226 AD, the northern side was dominated by a succession of Persian empires including the Median, Achaemenid, Seleucid and Parthian empires. Under the leadership of the Achaemenid king Darius the Great (Darius I), Persian ships found their way to the Persian Gulf. Persian naval forces laid the foundation for a strong Persian maritime presence in the Persian Gulf, that started with Darius I and existed until the arrival of the British East India Company, and the Royal Navy by mid-19th century AD. Persians were not only stationed on islands of the Persian Gulf, but also had ships often of 100 to 200 capacity patrolling empire’s various rivers including Shatt-al-Arab, Tigris, and the Nile in the west, as well as Sind waterway, in India.

The Achaemenid high naval command had established major naval bases located along Shatt al-Arab river, Bahrain, Oman, and Yemen. The Persian fleet would soon not only be used for peacekeeping purposes along the Shatt al-Arab but would also open the door to trade with India via the Persian Gulf.

Following the 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 the 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 had a flourishing commercial trade with China by the 4th century, having first established a connection with the far east in 185 AD.