Indus Valley Civilization: Discovery and Extent

The Indus Valley Civilisation (IVC), also known as the Harappan Civilisation, was one of the world’s earliest and most advanced urban cultures. Flourishing around 2500 BCE to 1750 BCE, it developed along the river valleys of the Indus and its tributaries, encompassing parts of present-day India and Pakistan. The civilisation is renowned for its urban planning, architecture, trade networks, and craftsmanship. Its discovery in the early 20th century revolutionised the understanding of India’s ancient past, pushing back the origins of Indian civilisation by several millennia.

Discovery of the Indus Valley Civilisation

1. Early References and Preliminary Explorations

Before its formal discovery, scattered archaeological finds hinted at an ancient urban culture in the north-western subcontinent. British archaeologists such as Alexander Cunningham, the founder of the Archaeological Survey of India (ASI), collected artefacts like seals and bricks from sites such as Harappa in Punjab during the 1870s, though their true significance was not recognised at the time.

2. Discovery of Harappa (1921)

The modern discovery of the civilisation began with excavations at Harappa in Montgomery District of Punjab (now in Pakistan) in 1921 by Daya Ram Sahni, an Indian archaeologist under the ASI. The site revealed well-baked bricks, seals with pictographic inscriptions, weights, and pottery — all pointing to an unknown urban culture predating the Mauryas and even the Vedic period.

3. Discovery of Mohenjo-Daro (1922)

In 1922, R. D. Banerjee discovered Mohenjo-Daro (“Mound of the Dead”) in the Larkana District of Sindh, Pakistan. Excavations led by John Marshall, the then Director-General of the ASI, brought to light a large, sophisticated urban settlement.
In 1924, Sir John Marshall announced the discovery of a “previously unknown civilisation”, contemporary with those of Egypt and Mesopotamia. Thus, the Indus Valley Civilisation emerged as the third great Bronze Age civilisation of the ancient world.

4. Subsequent Discoveries

Over the following decades, numerous sites were excavated across India and Pakistan, revealing the vastness and uniformity of the Harappan culture. Important archaeologists such as M. S. Vats, Rakhal Das Banerjee, E. J. H. Mackay, Mortimer Wheeler, and S. R. Rao contributed significantly to research and interpretation.

Geographical Extent of the Civilisation

The Indus Valley Civilisation covered a remarkably extensive area, larger than either the Egyptian or Mesopotamian civilisations. Its settlements spanned from the Himalayan foothills in the north to the Arabian Sea in the south, and from Baluchistan in the west to the Ganga-Yamuna Doab in the east.

1. Geographical Spread

• Western Boundary: Sutkagendor, near the Makran coast in Baluchistan (Pakistan), marks the westernmost site.
• Eastern Boundary: Alamgirpur in Meerut District, Uttar Pradesh, represents the easternmost extent.
• Northern Boundary: Manda in Jammu (Union Territory of Jammu & Kashmir) is the northernmost site.
• Southern Boundary: Daimabad in Maharashtra marks the southern limit of Harappan influence.

Thus, the civilisation’s area extended over 1.3 million square kilometres, encompassing parts of Punjab, Sindh, Baluchistan, Haryana, Rajasthan, Gujarat, Western Uttar Pradesh, and Northern Maharashtra.

2. Major River Systems

The civilisation flourished primarily along the Indus River and its tributaries — the Ravi, Beas, Sutlej, Chenab, and Jhelum — as well as the now-dry Saraswati-Ghaggar-Hakra river system, believed to have supported a dense cluster of settlements. The availability of fertile alluvial soil and access to water facilitated agriculture and trade.

Important Sites of the Indus Valley Civilisation

The Indus Valley Civilisation is represented by over 1,500 identified sites, broadly classified into urban centres and rural settlements.

1. Major Urban Centres

• Harappa (Punjab, Pakistan): First discovered site; large citadel, granaries, and burial sites found.
• Mohenjo-Daro (Sindh, Pakistan): One of the best-preserved cities; features include the Great Bath, drainage system, assembly halls, and residential areas.
• Dholavira (Kutch, Gujarat): Noted for its unique water conservation system, stone architecture, and three-part city layout.
• Kalibangan (Rajasthan): Shows evidence of early ploughed fields and fire altars, indicating both agricultural and ritual activities.
• Lothal (Gujarat): Important port town with a dockyard and evidence of maritime trade.
• Rakhigarhi (Haryana): One of the largest Harappan sites in India, with extensive housing and craft production areas.

2. Other Sites

• Banawali (Haryana): Residential planning and defensive walls; evidence of both pre-Harappan and mature Harappan phases.
• Ropar (Punjab): Findings include burials and evidence of trade with neighbouring regions.
• Surkotada (Gujarat): Fortified settlement, yielding remains of domesticated horse bones.
• Chanhudaro (Sindh): Centre for bead-making and crafts.
• Kot Diji (Pakistan): Early Harappan fortified settlement, showing the civilisation’s evolution.

Phases of the Indus Valley Civilisation

Archaeologists classify the Indus Valley Civilisation into three main phases based on urban development and artefacts:

1. Early Harappan Phase (c. 3300–2600 BCE):
   • Development of agricultural communities and small settlements.
   • Pottery, copper tools, and rudimentary town planning appear.
   • Sites: Kot Diji, Amri, Kalibangan (early levels).
2. Mature Harappan Phase (c. 2600–1900 BCE):
   • Peak of urbanisation — large planned cities, standardised bricks, drainage, weights, and seals.
   • Extensive trade with Mesopotamia and Central Asia.
   • Sites: Harappa, Mohenjo-Daro, Dholavira, Kalibangan, Lothal.
3. Late Harappan Phase (c. 1900–1300 BCE):
   • Gradual decline of urban centres; ruralisation of economy.
   • Regional cultures like Cemetery H and Jhukar emerge.
   • Sites: Rangpur, Ropar, Daimabad.

Causes for the Decline

The decline of the Indus Valley Civilisation remains debated, with scholars suggesting multiple interlinked causes:

• Environmental Changes: Shifting river courses (especially of the Saraswati) and floods.
• Climate Change: Gradual drying and declining monsoon patterns reducing agricultural productivity.
• Decline in Trade: Disruption of long-distance trade with Mesopotamia and other regions.
• Invasions or Internal Conflict: Possible pressure from Indo-Aryan migrations or internal social breakdown.
• Urban Decay: Over-exploitation of resources and breakdown of civic systems.

By around 1300 BCE, most urban centres had been abandoned, giving way to rural cultures in the Gangetic plains.

Significance of the Discovery

The discovery of the Indus Valley Civilisation profoundly altered the understanding of Indian history:

1. It proved that India’s urban civilisation predates the Vedic period, showing a continuous cultural development.
2. It demonstrated a high degree of scientific town planning, civic administration, and technological sophistication.
3. The vast extent indicated a strong political and cultural integration across regions.
4. Artefacts such as seals, weights, pottery, and tools reflect a complex economic and trade system.
5. It revealed that India’s civilisation was contemporary with Mesopotamia and Egypt, forming part of the global Bronze Age network.