Indus Valley Civilisation: Bronze Age Cities of South Asia

The Indus Valley Civilisation, also called the Harappan civilisation, was a Bronze Age culture that flourished in what is now Pakistan and north-western India, reaching its urban peak between about 2600 and 1900 BC. Contemporary with Old Kingdom Egypt and the cities of Sumer, it covered a larger area than either. Its planned cities, covered drains, standard weights and undeciphered script make it one of the most remarkable and least understood early civilisations.

Discovery: a civilisation found in the 1920s

Unlike Egypt or Mesopotamia, the Indus civilisation left no memory in later written traditions. Its ruins were long taken for ordinary old brick mounds. The British traveller Charles Masson described the mounds of Harappa after visiting them in 1826, and the archaeologist Alexander Cunningham visited the site several times between the 1850s and 1870s. In 1875 he published a stamp seal from Harappa with an unknown script, without realising how old it was.

Systematic work began only after the First World War. Daya Ram Sahni of the Archaeological Survey of India excavated at Harappa in 1920–21, and R. D. Banerji began digging at Mohenjo-daro in Sindh in 1922. Seals with the same script and animal designs turned up at both sites, roughly 600 kilometres apart. On 20 September 1924 John Marshall, Director-General of the Survey, announced the discovery of a previously unknown civilisation in the Illustrated London News.

Since then well over 1,000 sites have been identified, and some counts are much higher. Major excavations have continued at sites such as Harappa, Mohenjo-daro, Lothal, Kalibangan, Dholavira and Rakhigarhi.

Origins and phases

The civilisation grew out of a long farming tradition in the region. At Mehrgarh in Balochistan, people were cultivating barley and wheat and herding animals from about 7000 BC. Over the following millennia villages spread into the Indus plains, and regional cultures such as the Ravi, Hakra, Kot Diji and Sothi-Siswal developed.

Archaeologists usually divide the Indus sequence into three broad stages:

• Early Harappan (c. 3300–2600 BC): growing towns, some with walls, and the first signs that later became part of the Indus script.
• Mature Harappan (c. 2600–1900 BC): large planned cities, a shared material culture over a vast area, writing, standard weights and long-distance trade.
• Late Harappan (c. 1900–1300 BC): the big cities shrank or were abandoned and distinct regional cultures emerged.

These dates are approximate and vary from region to region, but the transition to the mature phase around 2600 BC appears to have been relatively quick.

Cities and town planning

The most famous features of the Indus cities are their planning and sanitation. Mohenjo-daro and Harappa were laid out with main streets running roughly north–south and east–west, dividing the city into blocks. Many towns had a raised, walled area in the west, often called the citadel, and a larger lower town to the east.

Houses were built of fired or mud bricks made in a standard ratio of about 1:2:4 for thickness, width and length. Many had private wells and bathing areas, and waste water ran into brick-lined drains along the streets, covered with bricks or stone slabs and fitted with inspection points. At Mohenjo-daro the Great Bath, a waterproofed brick tank on the citadel, is thought to have served ritual bathing.

Population figures can only be estimated. Mohenjo-daro may have housed somewhere around 30,000 to 40,000 people at its height, and Harappa perhaps 20,000 to 30,000. Estimates for the whole civilisation range widely, from about one million to five million people.

Economy, crafts and trade

The Indus economy rested on farming. People grew wheat, barley, pulses, sesame and, in some areas, millets and rice. They kept humped zebu cattle, water buffalo, sheep and goats. The Indus region is also one of the earliest places where cotton was grown and spun.

Indus craftworkers were highly skilled. They made long carnelian beads by drilling the hard stone with specially shaped drills, glazed faience ornaments, shell bangles, copper and bronze tools, and fine painted pottery. Small square stamp seals of steatite, carved with animals and short inscriptions, were probably used to mark goods and identify owners or officials.

Trade was organised with remarkable consistency. Cubical stone weights followed a common system, doubling from small units (1, 2, 4, 8, 16, 32, 64) and then rising in decimal multiples for larger weights. Indus seals, beads and weights have been found in the Persian Gulf and Mesopotamia, including at Ur. Mesopotamian texts refer to a distant land called Meluhha, which most scholars identify with the Indus region; Sargon of Akkad boasted that ships from Meluhha moored at his capital. Gulf trading centres such as Dilmun (Bahrain) and Magan (Oman) acted as intermediaries.

Writing, religion and power

The Indus script appears on about 4,000 known inscribed objects, chiefly seals, tablets and pottery. Most texts are very short, around five signs on average, and the script remains undeciphered. Without readable texts, almost everything about Indus beliefs and politics must be inferred from objects and buildings.

Religious life is therefore hard to reconstruct. Terracotta female figurines, fire altars at Kalibangan and Lothal, and seal images such as the seated horned figure often called the “Pashupati” seal have been interpreted as religious, but their meanings are debated.

Equally puzzling is the absence of obvious rulers. No palaces, royal tombs or monumental statues of kings have been identified, and there is little evidence of warfare. Some scholars suggest rule by merchant elites, priests or councils; others think each major city was an independent state with shared customs. The uniformity of bricks, weights and seals shows strong coordination, but how it was achieved is unknown.

Decline and transformation

After about 1900 BC the Indus cities changed. Mohenjo-daro and Harappa shrank, building standards fell, the script and standard weights went out of use, and long-distance trade dwindled. At the same time the number of small settlements grew in the east, in Haryana, Punjab and western Uttar Pradesh, and in Gujarat.

Most researchers now explain this as a gradual de-urbanisation with several causes. Climate records suggest a weakening of the summer monsoon around 2200–1900 BC, part of a wider dry phase also linked with the collapse of the Akkadian Empire in Mesopotamia. Rivers shifted course, and the Ghaggar-Hakra system lost much of its flow. The decline of trade with Mesopotamia may also have weakened urban elites.

The older idea that invading Aryans destroyed the Indus cities, popularised by the archaeologist Mortimer Wheeler in the 1940s, has been abandoned. Later study showed that the skeletons found in the upper levels of Mohenjo-daro were not victims of a single massacre.

Common myths

• Myth: the civilisation was destroyed overnight. In fact the decline was gradual and uneven, and many Indus traditions in crafts and farming continued in later South Asian cultures.
• Myth: it was confined to the Indus valley. Many important sites, including Rakhigarhi, Kalibangan, Dholavira and Lothal, lie outside the Indus valley proper, which is why many scholars prefer the term Harappan civilisation.
• Myth: the Indus script has been read. Many decipherments have been announced, but none has convinced the wider scholarly community.

Key people in its rediscovery

Because no Indus ruler or writer can be named, the people most closely associated with the civilisation are the archaeologists who uncovered it.

• John Marshall (1876–1958): as head of the Archaeological Survey of India he directed the early work at Mohenjo-daro and published the first major report, Mohenjo-daro and the Indus Civilization, in 1931.
• Daya Ram Sahni and R. D. Banerji: the Indian archaeologists whose excavations at Harappa and Mohenjo-daro first revealed the civilisation’s cities.
• Ernest Mackay and Madho Sarup Vats: led long seasons of excavation at Mohenjo-daro and Harappa in the late 1920s and 1930s.
• Mortimer Wheeler (1890–1976): excavated at Harappa and Mohenjo-daro in the 1940s and 1950 and promoted the now-rejected theory of an Aryan conquest.
• Later researchers: scholars such as George Dales, Jonathan Mark Kenoyer, Richard Meadow, Gregory Possehl, Rita Wright, B. B. Lal and R. S. Bisht reshaped understanding of the civilisation through new excavations at Harappa, Kalibangan, Dholavira and elsewhere.

By the numbers

Timeline

• c. 7000 BC: Farming begins at Mehrgarh in Balochistan.
• c. 3300 BC: Early Harappan phase; growing towns along the Indus and its tributaries.
• c. 2600 BC: Start of the mature urban phase; planned cities and the Indus script appear.
• c. 2300 BC: Akkadian texts mention ships from Meluhha, usually identified with the Indus region.
• c. 1900 BC: Major cities begin to decline; regional Late Harappan cultures develop.
• c. 1300 BC: Late Harappan traditions fade into later cultures of the region.
• 1826: Charles Masson visits the mounds at Harappa.
• 1920–22: Excavations begin at Harappa and Mohenjo-daro.
• 1924, 20 September: John Marshall announces the new civilisation.
• 1980: The ruins of Mohenjo-daro are inscribed as a UNESCO World Heritage Site.

Why it matters

The Indus Valley Civilisation shows that early urban life could take forms very different from the kingdoms of Egypt and Mesopotamia: large, orderly cities without obvious palaces or kings. Its achievements in town planning, sanitation and standardisation were unmatched in their time. As long as its script remains unread, it will remain one of the great open questions of world history.