Decline of Indus Valley Civilisation

A recent study claims that the Indus Valley Civilisation (IVC) declined not due to one catastrophic event, but due to centuries-long, recurring droughts that progressively weakened its cities, rivers, agriculture, and social structures.

Key Findings from the Study

• Central Conclusion:
  • The study indicates that the IVC did not collapse suddenly due to one catastrophic event.
  • Instead it reveals Harappa and other major IVC settlements were affected by a series of multi-decadal droughts between 3000–1000 BCE.
• Climate Reconstruction: Researchers used paleoclimate records (stalactites, stalagmites, lake levels) and climate model simulations to reconstruct rainfall and temperature patterns of the period.

Reasons for Decline of Civilisation

• Recurring Drought Cycles: Four major drought events, each lasting over 85 years, occurred between 2425–1400 BCE.
  • The most severe drought peaked around 1733 BCE, lasted ~164 years, and impacted the entire region.
• Hydrological Collapse: Prolonged drought led to Shrinking lakes and playas, Declining river flows, Soil desiccation, Reduced navigability, hurting trade.
• Climate Shift in the Pacific:
  • Early IVC prosperity coincided with La Niña-like conditions (3000–2475 BCE), causing wetter-than-modern monsoon seasons.
  • As the tropical Pacific warmed, annual rainfall dropped by 10–20%, and temperatures rose by 0.5°C, amplifying arid conditions.

Social and Economic Consequences

• Agricultural Stress: Drought made farming difficult, especially for settlements far from perennial rivers.
  • Adaptive Agricultural Practices: Harappans responded by switching crops, diversifying production, and shifting to drought-resilient farming.
  • Archaeo-botanical evidence shows a shift from wheat and barley to drought-resistant millets, indicating attempts to cope with aridity.
• Migration and Dispersal: Communities were forced to relocate repeatedly, reshaping the distribution of settlements along the Indus and its tributaries.
  • They diversified trade routes and moved settlements to more water-secure areas.
• Governance Strain: Reduced food supply and weak political structures combined with climatic pressures, pushing society toward decline and fragmentation.
• De-urbanisation:  The final century-long drought (3531–3418 BCE) coincides with archaeological evidence of large cities being abandoned and populations dispersing into smaller rural clusters.

Check Out UPSC CSE Books

Visit PW Store

Theories of Decline of the Indus Valley Civilization