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 Doha. Persian Gulf islands are often also historically significant, having been used in the past by colonial powers such as the Portuguese and the British in their trade or as acquisitions for their empires. Eight nations have coasts along the Persian Gulf: Bahrain, Iran, Iraq, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates. The gulf's strategic location has made it an ideal place for human development over time. Today, many major cities of the Middle East are located in this region. The wildlife of the Persian Gulf is diverse, and entirely unique due to the gulf's geographic distribution