Climate change behind rise and fall of ancient Indus Valley Civilisation, says study

The advanced Bronze Age civilisation lasted for 2,000 years and there are multiple theories about why it declined.

Friday 4 September 2020 12:16, UK

In this photograph taken on February 9, 2017, visitors walk through the UNESCO World Heritage archeological site of Mohenjo Daro some 425 kms north of the Pakistani city of Karachi. Once the centre of a powerful civilisation, Mohenjo Daro was one of the world's earliest cities -- a Bronze Age metropolis boasting flush toilets and a water and waste system to rival modern standards. Some 5,000 years on archaeologists believe the ruins could unlock the secrets of the Indus Valley people, who flouri
Image: The ancient Indus Valley Civilisation may have declined due to climate change
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Climate change caused the rise and fall of the ancient Indus Valley Civilisation, according to a new mathematical model of monsoon patterns.

The civilisation existed in the basins of the Indus River - spanning modern day northeast Afghanistan, most of Pakistan and northwestern India - and was contemporaneous with ancient Egypt and Mesopotamia.

It lasted for around 2000 years, until 1300 BC, are there are many competing hypotheses for its decline.

This figure shows the settlements of the Indus Valley Civilization during different phases of its evolution. RIT Assistant Professor Nishant Malik developed a mathematical method that shows climate change likely caused the rise and fall of the ancient civilization. Credit: Rochester Institute of Technology
Image: Settlements of the civilisation. Pic: RIT

Dr Nishant Malik, from the Rochester Institute of Technology in New York state, has come up with a new theory by developing a mathematical model of monsoon rainfall in the region over the past 5,700 years.

His model applied dynamical systems theory to paleoclimate data - for instance data on rainfall based on the presence of a particular isotope in stalagmites in a cave.

He has provided mathematical proof that the Indus Valley Civilisation flourished inbetween two major shifts in monsoon patterns.

TO GO WITH Pakistan-environment-conservation-animal,FEATURE BY ASHRAF KHAN In this photograph taken on September 13, 2014, a blind dolphin swims along the Indus river in the southern Pakistani city of Sukkur. Local legend has it that Pakistan's Indus River dolphin was once a woman, transformed by a curse from a holy man angry that she forgot to feed him one day. AFP PHOTO / Rizwan TABASSUM (Photo credit should read RIZWAN TABASSUM/AFP via Getty Images)
Image: The Indus River runs through much of modern day Pakistan

Just before the dawn of the civilisation, the rainfall pattern changed and provided the critical conditions necessary to sustain human life and nurture it.

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However, these monsoon dynamics eventually changed again, indicating a relationship with climate change and the decline of the civilisation.

Other theories explaining the civilisation's decline have suggested it was shattered by earthquakes or by an invasion of nomadic Indo-Aryans.

For its time, it was a remarkably advanced.

In this photograph taken on February 9, 2017, Pakistani caretaker at the UNESCO World Heritage archeological site of Mohenjo Daro, Ismail Mugheri, points out a two-story well used to collect drinking water at the site some 425 kms north of Karachi. Once the centre of a powerful civilisation, Mohenjo Daro was one of the world's earliest cities -- a Bronze Age metropolis boasting flush toilets and a water and waste system to rival modern standards. Some 5,000 years on archaeologists believe the ru
Image: Mohenjo-Daro had sewage systems thousands of years before London

It included the city of Mohenjo-Daro, meaning the "Mound of the Dead Men", which was built around 2,500 BC and only rediscovered in the 1920s.

Archaeological investigations of its cities have uncovered evidence of urban planning and the world's first known urban sanitation systems.

The first hydraulic engineering innovations were discovered there and sewage was disposed through underground drains connected to individual houses - something which didn't happen in London until the 19th century.