A-Brief-History-of-Saudi-Arabia

Arabia: The Land and Its Pre-Islamic History
border with the western coastal provinces is undefined. This was long
the heartland of the Bedouin, nomadic tribes, with its relatively few
settled inhabitants living in scattered oasis-based towns and villages. The
plateau, about 200 miles (320 km) wide, slopes downward from west
to east, descending from about 4,000 feet (1,360 m) to about 2,200 feet
(750 m). A low limestone escarpment in the vicinity of Riyadh, the Jebel
Tuwayq, one of several such formations in the region, forms the heart
of Najd. Marked by many oases and large salt marshes, the escarpment
swings north to south in an arc some 500 miles (800 km) long. Its western
face rises steeply some 300 to 750 feet (90–225 m) above the plateau,
the result of gradual erosion of softer rock and terrain around it.
Parallel and just east of Jebel Tuwayq is Ad Dahna, an 800-mile-long
(1,300 km), narrow desert, extending from the Great Nufud desert in
the north to the Rub al-Khali in the south. The sand’s high iron oxide
content gives it a reddish orange tint. Ad Dahna is bordered on the east
by the As Summan Plateau. The barren and rocky plateau, some 50 to
150 miles (80–240 km) wide, is marked by ancient river gorges and
isolated buttes bearing the signs of eons of erosion. The plateau drops
from an elevation of about 1,300 feet to about 750 feet (400–225 m).
Persian Gulf Coast
Flat lowlands and coastal plain extend east from the As Summan
Plateau for some 35 miles (60 km). The desolate landscape is generally
featureless and covered with gravel or sand. The northern portion is the
Ad Dibdibah Plain. To the south lies the Eastern Province, or Hasa. One
of the most fertile areas in Saudi Arabia, it includes the largest oasis in
the country. The capital of Hasa is the town of Hufuf. From here the
land descends toward the sandy shores of the Persian Gulf.
In the south of the Eastern Province the Al Jafurah sand desert, which
reaches the gulf near Dhahran, merges with the Rub al-Khali at its southern
end. The Persian Gulf coast is extremely irregular, merging sandy
plains, marshes, and salt flats (sabkhahs) almost imperceptibly with the
sea. The sea itself is shallow, with shoals and reefs extending far offshore.
The Deserts
Most of Saudi Arabia is desert. Average annual precipitation is about
4 inches (100 mm). Prevailing winds such as the southerly kauf and
the northwesterly shamal kick up severe dust storms. During the summer
season (mid-April–mid-October) daytime temperatures routinely
reach 113 degrees Fahrenheit (45 degrees Celsius). In coastal regions,
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