In 1901 the region (Jodhpur state) had an area of 93,424 km2.
Marwar is a sandy plain lying northwest of the Aravalli Range, which runs southwest-northeast through Rajasthan state. The Aravallis wring much of the moisture from the southwest monsoon, which provides most of India's rainfall. Annual rainfall is low, ranging from 10 cm to 40 cm. Temperatures range from 48 to 50 degrees Celsius in the summer, to below freezing point in winter. The northwestern thorn scrub forests lie next to the Aravalli Range, while the rest of the region lies in the Thar Desert.
The Luni River is the principal feature of the Marwar plains. It originates in the sacred Pushkar Lake of Ajmer District, and the main river flows through Marwar in a south-westerly direction until it finally disappears into the seasonal wetland of the Rann of Kutch in Gujarat. It is fed by tributaries that flow from the Aravallis. Irrigation from the river, and from wells near the river, support crops of wheat and barley.
The sandy tracts of Thar Desert in western Marwar [Maru Pradesh] are characterized by a harsh physical geography and a fragile ecology. High wind velocity, shifting sand dunes and very deep and saline water sources pose a challenge to sustained human habitation in the Thar.
The area is prone to devastating droughts. The Thar Desert is one of the most inhospitable landscapes on earth. Apart from the huge distances between hamlets and settlements here, the landscape is constantly shifting with the sand, as wind and sandstorms re-arrange the landscape. This, added to the lack of water in such an arid region, means that the villagers often find themselves migrating on foot across hundreds of miles towards neighboring states in search of water.