The Persian Gulf is a shallow marginal sea of the Indian Ocean located in West Asia, situated between the Arabian Peninsula and Iran (historically Persia). This body of water, which has an average depth of only 50 meters, is an extension of the Arabian Sea and the larger Indian Ocean. Its origin dates back to the Cenozoic era, related to the subduction of the Arabian plate under the Zagros Mountains. The name "Persian Gulf" has been in use since at least the 5th century BCE, when Greek sources named it after the prominent Achaemenid Empire in the region.
The Gulf connects to the Gulf of Oman and the Arabian Sea in the east via the narrow Strait of Hormuz, which is only about 56 kilometers wide at its narrowest point. This strait is the critical mechanism that links the Gulf's oil-producing nations to global markets. The countries bordering the Gulf include Iran, Iraq, Kuwait, Saudi Arabia, Bahrain, Qatar, the United Arab Emirates, and Oman (Musandam exclave).
The Gulf's primary significance is its connection to global energy security, as the surrounding countries hold nearly two-thirds of the world's proven crude oil reserves and about one-third of its natural gas reserves. This makes the Gulf the world's largest single source of petroleum. A major geopolitical concept connected to the Gulf is the naming dispute, which emerged in the 1960s with the rise of pan-Arabism. While internationally recognized as the Persian Gulf, Arab governments often refer to it as the Arabian Gulf. The strategic importance of the Gulf has led to conflicts, including the 1980–1988 Iran–Iraq War and the 1991 Gulf War.