Ramlat al-Sab'atayn

The Ramlat al-Sab'atayn (رملة السبعتين) is a desert region that corresponds with the northern deserts of modern Yemen (Al-Jawf, Marib, Shabwah governorates) and southwestern Saudi Arabia (Najran province).

It comprises mainly transverse and seif dunes and covers an area of about 60 by, roughly 10,000 sqmi.

The Ramlat as Sab'atayn includes part of what was known to medieval Arab geographers as the Sayhad (صيهد). It extends from al-Khawr to the edge of the Rub' al-Khālī or Empty Quarter. It includes the Yemeni muhafazahs of al-Jawf, Ma'rib and Shabwa.