The rub al khali (empty quarter) lies near the border between saudi arabia and:

Within this area lies a vast wilderness of sand, 'a desert within a desert so enormous and so desolate that even the Arabs call it the Rub'al-Khali or the Empty Quarter' (Thesiger 1959). ... The Rub'al-Khali crosses over from Saudi Arabia into western Oman and eastern Yemen.

Rub' al Khali
Sand dunes to the east of Liwa Oasis in the Emirate of Abu Dhabi, near the UAE's border with Saudi Arabia.

Location of the empty quarter in the Arabian Peninsula.

Length1,000 km (620 mi)

Width 500 km (310 mi)

Answeraquifer;

C.over 1 million refugees were displaced.