The Thar Desert (also known as the Great Indian Desert) is a desert located in the state of Rajasthan in northwest India. It continues into Pakistan as the Cholistan Desert. It is a region of constantly shifting sand dunes, with sparse vegetation in some areas.

The area turned to desert relatively recently: perhaps around 2000 BC - 1500 BC. Around this time the Ghaggar ceased to be a major river and now terminates in the desert. The area receives between 12 and 25 cm of precipitation annually.