Ever since the Indus Valley Civilization was discovered nearly a century ago, various theories have been proposed ranging from invasions to tectonic shifts, regarding what caused its demise. Now scientists have deduced conclusively that the fundamental reason for the collapse of this monumental civilization was none other than climate change that caused rivers to dry up and force the population to move eastward.
The Indus or Harappan Civilization flourished approximately 5000 years ago in the fertile valley of the Indian subcontinent and parallels the Mesopotamian and Egyptian civilizations in terms of achievement. Well planned townships, excellent drainage, granaries, trade routes and artwork formed the hallmark of this civilization, although the Indus Script is yet to be deciphered. Scientists from the Woods Hole Oceanographic Institution working in tandem with other international researchers between 2003 & 2008 found concrete evidence based on satellite and geological data, that it was indeed climate change that forced the settlers to abandon and move to fresh pastures. You can read more about it here