The geographic features of Rajasthan are the Thar Desert and the Aravalli Range, which runs through the state from southwest to northeast, almost from one end to the other, for more than 850 kilometres (530 mi). Mount Abu lies at the southwestern end of the range, separated from the main ranges by the West Banas River, although a series of broken ridges continues into Haryana in the direction of Delhi where it can be seen as outcrops in the form of the Raisina Hill and the ridges farther north. About three-fifths of Rajasthan lies northwest of the Aravallis, leaving two-fifths on the east and south direction.
The northwestern portion of Rajasthan is generally sandy and dry. Most of this region are covered by the Thar Desert which extends into adjoining portions of Pakistan. The Aravalli Range does not intercept the moisture-giving southwest monsoon winds off the Arabian Sea, as it lies in a direction parallel to that of the coming monsoon winds, leaving the northwestern region in a rain shadow. The Thar Desert is thinly populated; the town of Jodhpur is the largest city in the desert and known as the gateway of thar desert. The desert has some major districts like Jodhpur, Jaisalmer, Barmer, Bikaner and Nagour. This region receives less than 400 mm of rain in an average year. Temperatures can sometimes exceed 54 °C in the summer months or 129 degrees Fahrenheit and drop below freezing in the winter. The Ghaggar River, which originates in Haryana, is an intermittent stream that disappears into the sands of the Thar Desert in the northern corner of the state and is seen as a remnant of the primitive Saraswati river.
The Aravalli Range runs across the state from the southwest peak Guru Shikhar (Mount Abu), which is 1,722 metres (5,650 ft) in height, to Khetri in the northeast. This range divides the state into 60% in the northwest of the range and 40% in the southeast. The northwest tract is sandy and unproductive with little water but improves gradually from desert land in the far west and northwest to comparatively fertile and habitable land towards the east. The area includes the Thar Desert. The south-eastern area, higher in elevation (100 to 350 m above sea level) and more fertile, has a very diversified topography. in the south lies the hilly tract of Mewar. In the southeast, a large area within the districts of Kota and Bundi forms a tableland. To the northeast of these districts is a rugged region (badlands) following the line of the Chambal River. Farther north the country levels out; the flat plains of the northeastern Bharatpur district are part of an alluvial basin. Merta City lies in the geographical centre of Rajasthan.