In the light of fresh and exhaustive information now available on the ecology of vegetation of the Rajasthan desert, the reinterpretation of the published pollen diagrams reveals that there was increasing trend towards dryness until 5,000 years ago and thereafter between 5,000-3,000 years ago the environment was characterized by maximum warmth and dryness and by high velocity winds and dust storms. The precipitation which was within the range of 150-400 mm showed a gradient from the extreme

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... of the desert to its east. The renewed sand dune activity during the hypsithermal period had encroached upon the eastern tracts of the desert. The salt lakes which had originated about 10,000 years ago had already high salt content in their waters and during a continuous phase of recession in the entire Holocene rose once between 6,000-5,000 years B.P. The vegetation had comprised of Calligonum series and Prosopis-Capparis-Ziziphus series in the vicinities of Lunkaransar, Didwana and Sambhar and of Anogeissus-Acacia series in the vicinity of Pushkar lake. The earliest farming episode did not precede 5,000 years B.P. though inexplicable evidence of burning and disturbance of vegetation preceded it perhaps caused by natural means and grazing of animals. The subsequent desertification was caused by combined effect of climatic and biotic factors.