http://au.news.yahoo.com/thewest/a/-/world/13814840/huge-ancient-civilisations-c...Like their contemporaries in Egypt and Mesopotamia, the Harappans, who were named after one of their largest cities, lived next to rivers.
"Until now, speculations abounded about the links between this mysterious ancient culture and its life-giving mighty rivers," Giosan said.
Now Giosan and his colleagues have reconstructed the landscape of the plain and rivers where this long-forgotten civilizationdeveloped. Their findings now shed light on the enigmatic fate of this culture.
"Our research provides one of the clearest examples of climate change leading to the collapse of an entire civilization," Giosan said.
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All climate on Earth is driven by the sun, and so the monsoons were affected by the lower insolation, decreasing in force.
This meant less rain got into continental regions affected by monsoons over time."
Eventually, these monsoon-based rivers held too little water and dried, making them unfavorable for civilization.