Indus Valley Civilization

Chronology

The Indus Valley Civilization, also called the Harappan Civilization after Harappa, the first site excavated, is conventionally divided into three phases: Early Harappan (c. 3300–2600 BCE), when village farming cultures in the Indus basin began adopting standardized pottery, weights, and proto-urban features; Mature Harappan (c. 2600–1900 BCE), the period of full urbanization at Harappa, Mohenjo-daro, Dholavira, Rakhigarhi, and other cities; and Late Harappan, or "Localization" (c. 1900–1300 BCE), during which the great cities were abandoned or shrank and regional cultures replaced the integrated urban network. At its height the civilization covered more territory than contemporary Egypt and Mesopotamia combined, with well over a thousand identified sites spread across the plains of the Indus and the now-dry Ghaggar-Hakra river system, extending from Balochistan and the Makran coast to Gujarat and the upper Yamuna-Ganga doab, and north into Afghanistan at Shortugai.

Major Sites and Discovery

The civilization's existence was unknown to modern scholarship until the 1920s. Harappa, in Punjab, was excavated from 1920 under Daya Ram Sahni of the Archaeological Survey of India; Mohenjo-daro, on the Indus in Sindh, followed in 1922 under Rakhal Das Banerji, with both sites brought under the direction of ASI director-general John Marshall, who announced the discovery of a hitherto unknown civilization in 1924. Later excavation added Dholavira and Lothal in Gujarat, Kalibangan in Rajasthan, Rakhigarhi in Haryana — now understood to be among the largest Harappan sites — and Ganeriwala in Pakistan's Cholistan desert. Mohenjo-daro and Harappa are among the best-preserved Bronze Age cities anywhere; Dholavira, with its stepped water reservoirs and stadium-like structure, was inscribed as a UNESCO World Heritage Site in 2021.

Urban Planning and Infrastructure

Harappan cities were laid out on a grid of streets running roughly north-south and east-west, divided into a raised "citadel" containing large public structures and a larger "lower town" of residential and commercial buildings. Mohenjo-daro's Great Bath, a brick-built and bitumen-lined tank roughly 12 by 7 metres, is the best-known public structure and is generally interpreted as a site of ritual bathing. Houses were built of standardized fired brick, in a ratio found across the civilization's full geographic range, and many had private wells and bathrooms connected to covered street drains — a level of domestic sanitation not matched elsewhere in the Bronze Age world. Granaries at Harappa and Mohenjo-daro point to organized storage and, by inference, some mechanism for collecting and redistributing surplus grain, though no palace or unambiguous royal residence has been identified at any Harappan site.

Economy, Trade, and Craft

The Harappan economy rested on irrigated agriculture — wheat, barley, peas, sesame, and, distinctively, cotton, which the Indus region was among the first in the world to cultivate and weave — supplemented by cattle-keeping and river and coastal fishing. Trade extended overland into Central Asia and Afghanistan, source of lapis lazuli and tin, and by sea to Mesopotamia, where Harappan carnelian beads, seals, and other goods appear in Sumerian and Akkadian contexts; Mesopotamian texts refer to a trading partner called "Meluhha," widely identified with the Indus region. Lothal, in Gujarat, has a large brick-lined basin identified by its excavator as a dockyard, though this interpretation remains debated. Exchange was supported by a standardized system of cubical stone weights, following a consistent progression used across the civilization's full extent, and by carved steatite seals — many bearing animal motifs, most commonly the "unicorn" bull — pressed into clay to mark or authenticate goods.

Society and Religion

The absence of monumental palaces, elite tombs, or unambiguous temple structures has made Harappan social and political organization difficult to reconstruct, and there is no consensus on whether individual cities were governed by kings, councils, or some other arrangement, or whether the civilization had any overarching political authority at all. Terracotta figurines of women, often heavily ornamented, are common and are conventionally read as evidence of a fertility or mother-goddess cult, though this interpretation is not certain. A steatite seal from Mohenjo-daro depicting a horned, seated figure surrounded by animals — labelled the "Pashupati seal" by Marshall, who read it as an early form of the Hindu god Shiva in his aspect as Pashupati, "lord of animals" — remains one of the most discussed and most disputed images from the civilization; alternative readings identify the figure as a deity unconnected to later Hinduism, a composite animal, or a ritual specialist. Fire altars excavated at Kalibangan have likewise been read by some as evidence of ritual practices ancestral to later Vedic fire sacrifice, though this too is contested.

Art and Craft

Harappan metalworkers cast bronze and copper using the lost-wax method, and worked gold and silver into beads, bangles, and other ornaments found in some quantity at Mohenjo-daro, Harappa, and Lothal; stone-carvers and potters produced a large repertoire of geometric and figural decoration, and bead-making in carnelian, steatite, and faience was a major craft industry, with a specialized production center excavated at Chanhudaro. Two sculptures from Mohenjo-daro are singled out in most accounts of Harappan art: a small bronze figure known as the "Dancing Girl," cast in a confident, weight-shifted pose that is often cited as evidence of an early dance tradition, and a bearded limestone bust conventionally called the "Priest-King," wearing an armband and a trefoil-patterned robe, though neither the identity nor the social role of the figure it depicts is known.

The Indus Script

Thousands of short inscriptions, mostly on seals and averaging fewer than five signs, survive in the undeciphered Indus script. More than 400 distinct signs have been catalogued, and scholars disagree fundamentally over whether the script encodes a spoken language at all, or functioned instead as a system of non-linguistic symbols, such as clan or trade marks. No bilingual inscription comparable to the Rosetta Stone has been found, and the brevity of the surviving texts has so far defeated all proposed decipherments, including attempts to read the script as an early Dravidian, Indo-Aryan, or Munda language.

Decline

The Mature Harappan urban system broke down over several centuries beginning around 1900 BCE. The leading explanation ties this to climatic and hydrological change: weakening of the monsoon system and the drying up or eastward migration of the Ghaggar-Hakra river — often identified by tradition, though not conclusively by archaeology, with the Rigvedic Sarasvati — undermined the agricultural base that had sustained the largest cities. Cities were not destroyed violently or abandoned all at once; excavation shows gradual de-urbanization, with populations dispersing into smaller village settlements further east and south, craft standardization breaking down, and long-distance trade contracting. The older theory of a violent "Aryan invasion" ending the civilization, once widely repeated, has been abandoned by mainstream archaeology, which finds no evidence of large-scale warfare or conquest at Harappan sites; the identity and origins of the Indo-Aryan-speaking populations who appear in the textual record centuries later, and their relationship to the Late Harappan population, remain separately and actively debated among historians, linguists, and geneticists.