The Indus Civilization flourished between about 2600 and 1800 BC when it collapsed into regional cultures at the Late Harappan stage. According to Parpola the collapse was due to a combination of several factors like over-exploitation of the environment, drastic changes in the river-courses, series of floods, water-logging and increased salinity of the irrigated lands. Finally the weakened cities would have become easy victims of the raiders from Central Asia, whose arrival heralded a major cultural discontinuity in South Asi

Parpola's new hypothesis will have to be examined in detail by specialists in South Asian history and Indo-European linguistics. So far as the Indus Civilization is concerned the main implication of the new theory seems to be that the Aryan-Dasa conflict recorded in the earliest portions of the Rigveda is the story of the hostilities and eventual fusion of two Aryan tribes, which took place before their entry into the Indian sub-continent and has thus no relevance to the demise of the mature phase of the Indus Civilization.

be that the Aryan-Dasa conflict recorded in the earliest portions of the Rigveda is the story of the hostilities and eventual fusion of two Aryan tribes, which took place before their entry into the Indian sub-contine