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
Gulf of Oman desert and semi-desert of mangroves at Khor Kalba Nature Reserve on the Gulf of Oman in the UAE near the border with Oman. Gulf of Oman desert and semi-desert The Gulf of Oman desert and semi-desert is a coastal ecoregion on the Persian Gulf and the Gulf of Oman in Oman and the United Arab Emirates at the northeastern tip of the Arabian Peninsula. The climate is hot and dry; the ecoregion contains a mixture of habitats including mangrove swamps, lagoons and mudflats on the coast, and gravelly plains and savanna with thorny acacia trees inland. The mangrove areas are dominated by "Avicennia