Ramlat al-Sab'atayn

The Ramlat al-Sab'atayn (Arabic: 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).^[1]

Yemeni Desert.

It comprises mainly transverse and seif dunes and covers an area of about 100 by 240 kilometres (60 by 150 mi), roughly 26,000 square kilometres (10,000 sq mi).^[2]

The Ramlat as Sab'atayn includes part of what was known to medieval Arab geographers as the Sayhad (Arabic: صيهد, romanized: Ṣayhad). 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.