Write a note on the decline of Indus Valley Civilization.

Causes for the Decline of the Indus Valley (Harappan) Civilization (c. 1900–1700 B.C.):

The decline of the mature Harappan civilization was not caused by a single catastrophic event, but a multi-causal combination of ecological, environmental, and socio-economic disruptions:

• 1. Desiccation and Drying up of Saraswati / Ghaggar-Hakra River System:
  • Tectonic shifts diverted Yamuna and Sutlej waters away from the Ghaggar-Hakra channel, causing the desertification of the central Harappan heartland (Kalibangan, Banawali).
• 2. Catastrophic Flooding and Tectonic Uplifts (M.R. Sahni & Robert Raikes):
  • Massive tectonic damming of the Indus River inundated Mohenjo-daro multiple times (evidenced by 7 layers of silt/rebuilding).
• 3. Climate Change & Aridity (Gurdip Singh):
  • Weakening of the South-West Monsoon around 2000 B.C. decreased agricultural yields, collapsing the urban grain supply.
• 4. Aryan Invasion / Warfare Theory (Outdated - Wheeler & Childe):
  • Historically argued based on Rigvedic Indra as Purandara (destroyer of forts) and skeletons at Mohenjo-daro; largely refuted by modern archaeological genetics.
• 5. Collapse of Long-Distance Trade with Mesopotamia: Ruined the urban mercantile economy, forcing populations to de-urbanize into rural Chalcolithic settlements.