What makes the Arabian Peninsula a region

The landmass, and the part of it filed here

Encyclopaedia Britannica gives the peninsula about 3,100,000 square kilometres, with the Red Sea along its west, the Gulf of Aden and the Arabian Sea along its south, and the Gulf of Oman and the Persian Gulf along its east. Three of those edges settle themselves. The fourth does not: the peninsula and the Syrian Desert run into one another in the north with no line between them, and the convention is to take the northern boundaries of Saudi Arabia and Kuwait as the limit. A landmass whose only landward edge is a convention cannot produce a membership list out of geography alone.

Seven states hold territory on it. The catalogue files six of them under Persian Gulf, after the water their coasts front, and keeps this region for the state whose shoreline does not reach that water. Yemen faces the Red Sea, the Gulf of Aden and the Arabian Sea instead.

What crosses the inland borders

The Rub al Khali covers about 650,000 square kilometres, lying mainly in southeastern Saudi Arabia with smaller portions in Yemen, Oman and the United Arab Emirates. Sand of that extent is part of why the peninsula's inland boundaries were fixed late. The Saudi Arabian and Yemeni line was settled by a treaty signed at Jeddah on 12 June 2000, in force from 4 July that year, closing an argument running back to an agreement made at Taif in 1934. The maritime segment it drew runs under 100 nautical miles in three parts and stops without a defined terminal point.

The council that took six

The charter of the Gulf Cooperation Council was signed at Abu Dhabi on 25 May 1981 by Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates, and that roster has not changed since. It is the peninsula with Yemen left out. After the boundary treaty, Yemen was admitted to council bodies covering education, labour, sport and health as a step towards accession. The accession did not follow, and the application has stood at candidacy.

The other coast

At the Bab el-Mandeb the Red Sea narrows to about 30 kilometres between the peninsula and the Horn of Africa, and tanker traffic is held to two channels of roughly three kilometres each. About 6.2 million barrels a day of crude oil, condensate and refined products passed through in 2018.

Where the edges are argued

The split made here is one reading. A second treats the peninsula as a single region and a gulf as a coastline rather than a category, which keeps all seven states in one group. The UN Statistics Division uses neither: its M49 standard files every one of them under Western Asia, and says of its own groupings that they are a statistical convenience carrying no political meaning. All three put the same land on the same peninsula and differ over whether a shoreline is grounds for a separate file. The page for each country states the grouping applied to it.