Ancient History Prelims cum Mains

How climate change may have changed Harappan society, led to its decline

The News

  • Recent studies indicate that variations in monsoonal rainfall due to climate change may have influenced the decline of the Indus Valley Civilisation.

Key Findings

  • According to a study, the pattern of changes in monsoonal rainfall may have led to decline of Indus Valley Civilization.
  • At first, a wetter winter monsoon may have led to expansion and de-urbanisation of the Indus Valley Civilisation.
  • Eventually, as the winter monsoon declined the agricultural civilization of rural Harappans also declined.

Chronology of Harappan Civilzation

  • Harappan civilization is divided into
  1. Early Harappan Phase: c. 3500 – 2600 B.C.
  2. Mature Harappan Phase: c. 2600 -1900 B.C.
  3. Late Harappan Phase: c. 1900 – 1300 B.C.
  • The early phase was mostly agrarian, centered on villages;
  • The Mature phase was characterised by the development of cities.
  • The third phase was one of de-urbanisation where several cities were abandoned.

Harappan conditions

  • The study named ‘Neoglacial climate anomalies and the Harappan metamorphosis’ reconstructed the behavior of Indian Monsoon for about 6000 years.
  • Harappans basically relied primarily on fluvial inundation for winter crops and on rain for summer crops.
  • According to the study in the first two phases, climate was warm and wet due to a stable monsoonal pattern.
  • This ensured a surplus of agricultural produce during these phases, slowly leading to the evolution of cities.
  • Harappans reached their “urban peak” or the ‘Mature Phase’ between 2600 and 1,900 bc.

How did the decline start?

  • The downfall of the civilisation starts with the de-urbanisation phase.
  • De-urbanisation was due to a decrease in temperature and decline in summer monsoon rainfall in the region.
  • The trigger for the urban Harappan collapse was thus due to the decline of the summer monsoon.
  • This period also saw an increase in winter monsoon.
  • This also reduced the flow of Indus River and its tributaries which led to migration of the people further east towards Ganga.
  • This triggered the metamorphosis of the urban Harappan civilisation into a rural society and further expansion to east.
  • The winter monsoon also weakened between 1300bc-1000bc.
  • This could have played a major role in the demise of the rural late Harappans also.

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