Indus Valley Civilization Timeline

Around 1900 BCE signs of a gradual decline began to emerge, and by around 1700 BCE most of the cities had been abandoned. During approximately 1900 to 1700 BCE, multiple regional cultures emerged within the area of the Indus civilisation.

According to Possehl, after 1900 BCE the number of sites in today's India increased from 218 to 853, reflecting the shift of population eastward as the civilisation declined.

The Indus Valley climate grew significantly cooler and drier from about 1800 BCE, linked to a general weakening of the monsoon at that time. The IVC residents did not develop irrigation capabilities, relying mainly on seasonal monsoons leading to summer floods.

Harvard archaeologist Richard Meadow points to the late Harappan settlement of Pirak, which thrived continuously from 1800 BCE to the time of the invasion of Alexander the Great in 325 BCE.

Image source: Duke Pirak

By around 1700 BCE most of the cities of the Indus Valley Civilisation had been abandoned, though many sites continued to be occupied for some centuries, although their urban features declined and disappeared.

According to Andrew Lawler, excavations along the Gangetic plain show that cities began to arise there starting about 1200 BCE, just a few centuries after Harappa was deserted. At Bhagwanpura, an overlap exists between Late Harappan pottery and Painted Grey Ware pottery associated with Vedic culture.

As of 2016, archaeological data suggests that the material culture classified as Late Harappan may have persisted until at least c. 1000–900 BCE and was partially contemporaneous with the Painted Grey Ware culture.

Subsequent examinations of the skeletons by Kenneth Kennedy in 1994 showed that marks on skulls once attributed to Aryan invasion violence were caused by erosion, not violence, undermining Wheeler's 1953 invasion hypothesis.

As of 2016 many scholars believe that drought, and a decline in trade with Egypt and Mesopotamia, caused the collapse of the Indus civilisation, rather than conquest or migration.

In 1829, Masson travelled through the princely state of Punjab, gathering useful intelligence for the Company in return for a promise of clemency, passing by the ruins of Harappa.

Image source: Charles Masson

In 1842, Masson included his observations of Harappa in the book Narrative of Various Journeys in Baluchistan, Afghanistan, and the Punjab.

Despite early reports, Harappa was raided even more perilously for its bricks after the British annexation of the Punjab in 1848–49, stripping much of the site's upper layer.

Image source: Harappa

Three years after the dissolution of the East India Company and the establishment of Crown rule in India, archaeology on the subcontinent became more formally organised with the founding of the Archaeological Survey of India (ASI), culminating eventually in the discovery of Harappa and Mohenjo-daro.

Image source: Archaeological Survey of India

Alexander Cunningham, the Survey's first director-general, who had visited Harappa in 1853, visited again to survey a site whose entire upper layer had been stripped. Though his goal of proving it a lost Buddhist city mentioned by Xuanzang proved elusive, he published his findings in 1875.

Image source: Alexander Cunningham

Archaeological work at Harappa lagged until a new viceroy of India, Lord Curzon, pushed through the Ancient Monuments Preservation Act 1904, and appointed John Marshall to lead the ASI.

In 1923, on his second visit to Mohenjo-daro, Banerji wrote to Marshall postulating an origin in 'remote antiquity', noting congruence of artifacts with those of Harappa. Later that year, Vats noted the same specifically about seals and script found at both sites.

Image source: Mohenjo-daro

Systematic excavations began at Mohenjo-daro in 1924–25, followed by those of Hargreaves (1925–1926) and Ernest Mackay. By 1931, much of Mohenjo-daro had been excavated.

By 1924, Marshall had become convinced of the significance of the finds, and on 24 September 1924 made a tentative but conspicuous public intimation in the Illustrated London News, comparing the discovery to Schliemann at Tiryns and Mycenae.

Image source: John Marshall (archaeologist)

John Marshall identified prominent features of the Indus religion: a Great Male God and a Mother Goddess; deification or veneration of animals and plants; symbolic representation of the phallus (linga) and vulva (yoni); and use of baths and water in religious practice.

Image source: Religion of the Indus Valley Civilisation

Occasional excavations continued at Mohenjo-daro, such as one led by Mortimer Wheeler, a new director-general of the ASI appointed in 1944, and including Ahmad Hasan Dani.

Image source: Mortimer Wheeler

After the partition, Mortimer Wheeler oversaw the establishment of archaeological institutions in Pakistan, later joining a UNESCO effort tasked to conserve the site at Mohenjo-daro.

After the partition of India in 1947, when most excavated sites lay in territory awarded to Pakistan, the ASI carried out large numbers of surveys and excavations along the Ghaggar-Hakra system in India. In Pakistan, archaeological work on early sites was left largely to foreign archaeologists.

Image source: Partition of India

Mohenjo-daro in the lower Indus Valley was declared a UNESCO World Heritage Site in 1980 as 'Archaeological Ruins at Moenjodaro', recognising its importance as one of the five major urban centres of the Mature Harappan period.

Excavation at Dholavira started under an archaeological team from Gujarat State Department of Archaeology and the Museum of the University of Pennsylvania in 1982–83.

Image source: Dholavira

Photos of many of the thousands of extant inscriptions are published in the Corpus of Indus Seals and Inscriptions (1987, 1991, 2010), edited by Asko Parpola and his colleagues; the most recent volume republished photos taken in the 1920s and 1930s of hundreds of lost or stolen inscriptions.

Image source: Indus script

By 2002, over 1,000 Mature Harappan cities and settlements had been reported, of which just under a hundred had been excavated, mainly in the general region of the Indus and Ghaggar-Hakra rivers and their tributaries.

While the Indus Valley Civilisation is generally characterised as a literate society, Farmer, Sproat, and Witzel (2004) argued that the Indus system did not encode language but was similar to non-linguistic sign systems symbolising families, clans, gods, and religious concepts. A 2009 study by P.N. Rao et al. countered this view.

As of 2008, about 616 sites have been reported in India, whereas 406 sites have been reported in Pakistan. As of 1977, about 90% of Indus script seals and inscribed objects discovered were found at sites in Pakistan along the Indus river.

In his 2019 study of the Harappan and Indus copper industry, Brett Hoffman analysed extensive copper/bronze assemblages from Harappa covering 3300 to 1700 BCE, challenging some older broad interpretations of bronze production.

Image source: Indus Valley Civilisation

In 2019, a study published by Shinde et al. examined genetic evidence relating to the people of the Indus Valley Civilisation, contributing to debates about ancestry and migration in ancient South Asia.

Dholavira in western Gujarat was declared a UNESCO World Heritage Site in 2021 as 'Dholavira: A Harappan City', joining Mohenjo-daro among the recognised major urban centres of the Indus Valley Civilisation.