Name the asian desert that boarders africa

This is the Arabian desert . It is commonly referred to as the desert of the Arab Peninsula

It occupies an area of 900,000 square miles. On the south it is bordered by the Gulf of Aden which borders  the country of Somalia in Africa and on the northeast, the Arabian desert merges imperceptibly into what is called Arab Asia through the Syrian steppe.

The Arabian desert borders the Nile River Valley on its west and the Gulf of Suez on the eastern end, which makes it essentially surrounded by water on all sides with the exception of the northeast  corner that connects it with the Asian continent. 

20: 5

explanation:

about 20% of the world's population lives in   southwest asia, but on less than 5% of the world's   land area.