The Central Region, considered the heartland of Saudi Arabia both physically and culturally, is a vast eroded plateau, consisting of areas of uplands, broad valleys and dry rivers. The area also contains a number of marshes. These are thought to be the remnants of inland seas which existed in ancient geological times. Most of the Central Region is arid, with some oases in the north around Qasim.
The area around Kharj which lies south of Riyadh has now become a major source of wheat, part of the Kingdom's burgeoning agricultural industry; while 300 miles to the north of Riyadh lies the Qasim region, an even larger farming area which has contributed on a massive scale to the Kingdom's self-sufficiency in wheat and poultry.
The climate of the region is hot and dry in summer and cold in winter. Summer temperatures sometimes exceed 45 degrees centigrade, while in winter the temperature falls to 5 degrees centigrade or lower.