The purpose of the present paper is to unravel the spatio-temporal changes in guar cultivation and factors responsible in Rajasthan from 1990-91 to 2020-21. This paper has three folds. In the first part, the spatial patterns of guar cultivation for the time period 1990-91, 2005-06 and 2020-21 are explained. The second part finds out the changes in guar cultivation during study period. While conclusions are drawn and suggestions are made in third part. The study has found that the guar area has increased from 9.17 percent in 1990-91 to 9.89 percent in 2005-06 and 10.84 percent in 2020-21 and registered an overall increase of 1.67 percent in the study region. Jaisalmer district has recorded highest area of 44.91 percent under its cultivation, while Bikaner and Hanumangarh districts have noted highest positive change of 18.85 percent and 24.42 percent, respectively, during study period. It is also observed that districts of Jaisalmer, Barmer, Jodhpur, Bikaner, Ganganagar, Hanumangarh, Churu, Nagaur, Jhunjhunu, and Sikar have registered over 6 percent of total cropped area under guar cultivation, which shows that its cultivation is largely confined to the Thar Desert of India and reasons identified are sandy soil, high temperature, low rainfall, low to moderate extent of irrigation, traditionally guar growing areas, high demand and high price that ensure higher and assured economic returns to farmers. It is suggested that guar cultivation should be encouraged by the Government policies, State Agricultural Universities, and Agricultural Research Institutes. The study is based on secondary sources of data, which is obtained from Statistical Abstracts of Rajasthan. Three time periods of 1990-91, 2005-06 and 2020-21 are selected, statistical methods and cartographic techniques are used.