Geography of India of the world's most intensely farmed areas. The main crops grown are rice and wheat, which are grown in rotation. Other important crops grown in the region include maize, sugarcane and cotton. The Indo-Gangetic plains rank among the world's most densely populated areas. The Thar Desert (also known as "the deserts") is by some calculations the world's seventh largest desert, by some others the tenth. It forms a significant portion of western India and covers an area of . The desert continues into Pakistan as the Cholistan Desert. Most of the Thar Desert is situated in Rajasthan, covering 61% of
Thar Desert highly mobile due to strong winds occurring before the onset of the monsoon. The Luni River is the only river integrated into the desert. Rainfall is limited to per year, mostly falling from July to September. Salt water lakes within the Thar Desert include the Sambhar, Kuchaman, Didwana, Pachpadra and Phalodi in Rajasthan and Kharaghoda in Gujarat. These lakes receive and collect rain water during monsoon and evaporate during the dry season. The salt is derived by the weathering of rocks in the region. Lithic tools belonging to the prehistoric Aterian culture of the Maghreb have been discovered in Middle