Ad-Dahna Desert Ad-Dahna Desert The ad-Dahna Desert is the central division of the Arabian Desert. It is a corridor of sandy terrain forming a bow-like shape that connects an-Nafud desert in the north to Rub' al-Khali desert in the south. Its length is more than 1,000 km siding Twaik Mountains from the east and does not exceed 80 km in width. It is also considered the geographical margin separating Al-Ahsa Province from Najd. Al-Dahna Desert is therefore the string that connects the great deserts of Saudi Arabia. The desert is a series of seven successive deserts, separated from one another by plains.
Jabal Aja Protected Area Area because of the richness of its plant life and the presence of many endemic and relict plant species. The reserve offers a refuge to plants from the Mediterranean and Irano-Turanian Regions in an area that otherwise forms part of the Saharo-Arabian Region. About 355 species of plant have been recorded in the reserve, including the plants found in the adjoining desert area of An Nafud. The plains have deep sandy-loam soils and the dominant plant is "Haloxylon salicornicum", with the desert gourd being common and "Asphodelus tenuifolius" occurring in depressions. The annual plants "Stipa tortilis", "Picris cyanocarpa" and "Anthemis"