Decline of the Harappan Civilisation
Analyse the environmental, climatic, hydrological, tectonic, and invasion theories of de-urbanisation (1900 BCE - 1300 BCE) for UPSC GS-1.
1. Climatic, Ecological, and Environmental Theories
Environmental and climatic theories argue that the delicate balance of the semi-arid Indus basin was disrupted by natural shifts and human over-exploitation:
Ecological Imbalance Theory: Walter Fairservis proposed that the Harappans over-exploited their environment. The massive requirements for fuel (for firing millions of baked bricks) led to severe deforestation. Combined with intensive cattle grazing, this depleted forest cover and soil nutrients, rendering the region vulnerable to erosion, flash floods, and agricultural collapse.
Aridity and Climate Change: Gurdip Singh analyzed pollen profiles from salt lakes in Rajasthan (Sambhar, Didwana, Lunkaransar). His research showed that the region enjoyed high rainfall from 3000 BCE to 1800 BCE, supporting intense agriculture. Around 1800 BCE, a global climatic event initiated a prolonged phase of aridity, leading to agricultural failure.
Drying of the Ghaggar-Hakra River (Saraswati): Proponents like Aurel Stein, A.N. Ghosh, and later satellite studies showed that the Ghaggar-Hakra river system dried up due to tectonic movements that diverted its major glacial tributaries (Sutlej to the Indus and Yamuna to the Ganges). The drying up of this fertile belt forced the abandonment of major urban sites like Kalibangan and Banawali.
2. Hydrological, Tectonic, and Pathological Theories
These theories attribute the collapse to sudden physical catastrophes or health epidemics:
Tectonic Damming and Flooding: M.R. Sahni, Robert Raikes, and George Dales proposed that tectonic activity near Sehwan (lower Indus valley) raised a barrier across the river channel. This blocked the flow of the Indus, forming a giant reservoir. Mohenjo-daro was repeatedly submerged under still water for long periods, as evidenced by deep layers of silty clay containing water-worn pottery at various occupational levels.
River Migration Theory: H.T. Lambrick refuted the tectonic damming theory, arguing that the Indus River shifted its course away from Mohenjo-daro. This river migration deprived the city of its water supply for domestic use and agriculture, leading to abandonment and desertification.
Endemic Epidemics (Paleopathology): K.V.R. Kennedy analyzed human skeletal remains from Mohenjo-daro. His pathological studies revealed that rather than dying from warfare, a high percentage of the population suffered from endemic malaria, anemia (porotic hyperostosis), and joint diseases, pointing to demographic collapse driven by epidemics.
3. Aryan Invasion, Trade Collapse, and Decentralisation Theories
These explanations look at socio-economic, external, and administrative factors:
The Aryan Invasion Theory: Proposed by R.P. Chanda (1926) and popularized by Mortimer Wheeler (1947). Wheeler cited Rigvedic hymns mentioning Indra as *Purandara* (destroyer of forts) and pointed to a group of 37 unburied skeletons found in the streets and rooms of Mohenjo-daro as evidence of a final massacre. However, this theory was thoroughly refuted by George Dales, who showed that the skeletons belonged to different occupational phases and showed signs of healed wounds and proper burials rather than a single catastrophe.
Socio-Economic Trade Collapse: Shereen Ratnagar argued that the decline of long-distance trade with Mesopotamia (recorded in cuneiform tablets where mentions of 'Meluhha' cease after 1900 BCE) caused a severe loss of elite wealth and control. Without luxury goods to distribute as prestige items, the central administration crumbled, causing cities to decay.
Systemic State Collapse: The collapse of the civic administrative machinery is marked by the disappearance of uniform weights, seals, brick ratios (4:2:1), and script. The urban population dispersed into smaller, rural settlements in the east and south (Gujarat, Punjab, western Uttar Pradesh).
Chronology of Harappan Decline
- c. 1900 BCE — Mature Harappan End: Beginning of de-urbanisation, decay of civic authority, and abandonment of script, seals, and standardized weights.
- c. 1800 BCE — Late Harappan Migration: Pollen records show sharp drop in rainfall; tectonic movements divert tributaries of the Ghaggar-Hakra river system.
- c. 1700 BCE — De-urbanised Regionalism: Emergence of localized, rural successor cultures (Jhukar, Cemetery H) showing simplified crafts and pottery styles.
- c. 1300 BCE — Final Agrarian Assimilation: Complete absorption of Harappan cultural traits into regional Chalcolithic agrarian farming communities.
Key Questions & Answers
- Who proposed the Ecological Imbalance Theory for the Harappan decline?
- Walter Fairservis , arguing that resource depletion and deforestation led to agricultural failure.
- What did Gurdip Singh analyze to propose the aridity theory?
- Pollen profiles from salt lakes in Rajasthan (Sambhar, Didwana, Lunkaransar), which showed a decline in rainfall around 1800 BCE.
- Who proposed the Tectonic Damming theory causing siltation at Mohenjo-daro?
- M.R. Sahni, Robert Raikes, and George Dales .
- Why is Mortimer Wheeler's Aryan Invasion theory refuted today?
- Skeletons at Mohenjo-daro belong to different stratigraphic layers , show signs of healed wounds, and lack weapons or armor nearby.
- What is Shereen Ratnagar's theory on the Harappan decline?
- Trade Collapse Theory , stating that the breakdown of long-distance Mesopotamian trade dismantled administrative structures.
- Which paleopathologist identified malaria as a major cause of demographic decline?
- K.V.R. Kennedy , through examination of skeletal remains from Mohenjo-daro.
Memory Aids
- Mnemonic: Decline Scholars (F-S-R-W): F = Fairservis (Ecological Imbalance), S = Singh (Rain/Aridity), R = Raikes (Water/Floods/Tectonic Dams), W = Wheeler (War/Aryan Invasion).
Common Exam Traps
- Trap 1: Avoid statements claiming that the Harappan civilisation was destroyed in a single year or event. The decline was a gradual de-urbanisation and ruralisation process spanning over 500 years.
- Trap 2: Watch out for options asserting that Wheeler's invasion theory is archaeologically proven. The theory is refuted due to stratigraphic discrepancies and lack of military remains.
- Trap 3: Do not assume that Gurdip Singh's aridity theory is universally accepted. It remains a debated climatic reconstruction.
- Trap 4: Avoid options claiming that the Harappans used iron weapons for warfare. Iron was completely unknown in the Bronze Age Harappan Civilisation.
- Trap 5: Watch out for statements claiming that the Ghaggar-Hakra river system was a purely seasonal stream in the Mature period. It was glacier-fed via the Sutlej and Yamuna before tectonic diversions.