The civilisation was the most widespread among the ancient civilisations, covering an area about 1.5 million sq km - now comprising modern India, Pakistan, Baluchistan and Afghanistan.
Kolkata: The famed Indus Valley civilisation remained under severe drought for about 900 years around 4,350 years ago, which led to the people to abandon their settlements and migrate to south and and eastward regions of India, according to a study by IIT Kharagpur.
The civilisation was the most widespread among the ancient civilisations, covering an area about 1.5 million sq km - now comprising modern India, Pakistan, Baluchistan and Afghanistan.
It had a well-developed infrastructure, architecture, metallurgy, besides having trade relations and cultural ties with other concurrent civilizations across the world.
A team led by Professor Anil K Gupta of Department of Geology and Geophysics at the Indian Institute of Technology Kharagpur has observed that the drought-like phase for the period of 900 years led to reduction in water supply because of the "very weak" Indian summer monsoon, which was under the influence of strong El Nino activity, the climate cycle in the Pacific ocean.
This decreased the moisture transport and in turn the snow deposition in northwest Himalaya, which have been a major source of water supply in the Indus river and its tributaries thus affecting agriculture production, an IIT Kharagpur statement said on Monday.