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
Gazetteer of the Persian Gulf, Oman and Central Arabia Gulf States and Saudi Arabia" from the 17th to early 20th century. Beginning in the 20th century, the British Empire sought to strengthen its connections to British-controlled India which in turn resulted in a greater interest in the Persian Gulf region, culminating in the visit of the Viceroy of India Lord Curzon to the Gulf in 1903. To ensure that British agents in the region were adequately informed and prepared to strengthen their influence in the region, a light-weight and easily accessible handbook was needed. In November 1903, the British authorities commissioned John Gordon Lorimer, a member of the Indian