A long arc, not a single event
The Indus Valley civilization did not appear and disappear in a moment. Its story stretches over several thousand years, from the first farming villages to the decline of its large cities, and the change at the end took place over generations. The dates below are approximate and differ from region to region.
| Stage | Approximate dates | Main features |
|---|---|---|
| First farmers | from c. 7000 BCE | Farming and herding villages such as Mehrgarh |
| Early Harappan | c. 3300-2600 BCE | Regional cultures, growing towns, craft specialisation |
| Mature Harappan | c. 2600-1900 BCE | Large planned cities, shared weights and seals |
| Late Harappan | c. 1900-1300 BCE | Smaller settlements, shifting population |
Stage one: farmers in the hills and plains
At Mehrgarh, on the edge of the Kachi plain in Baluchistan, people were growing wheat and barley and keeping cattle, sheep and goats from about 7000 BCE. Over the following millennia farming spread to the Indus plains. Pottery, copper working and trade in stone and shell gradually grew. These communities were the base on which later cities depended.
Stage two: towns and regional cultures
In the fourth and early third millennia BCE, settlements on the Indus plains and the Ghaggar-Hakra region grew larger, some with defensive walls and planned layouts. Different regions had different pottery and customs. Evidence for exchange of goods such as carnelian and shell shows that communities were already in contact. This long local development is one reason most scholars think the cities arose from within the region and not as imports from elsewhere.
Stage three: the urban peak
From about 2600 BCE the largest cities, Mohenjo-Daro, Harappa, Dholavira and others, took shape, with standard bricks, weights, seals and a script. Trade with the Gulf and Mesopotamia flourished, and craft production expanded. Compared with the great Mesopotamian empires of the same age, the Indus cities appear less hierarchical in their remains, though how they were governed is debated.
Stage four: signs of strain
Around the end of the third millennium BCE, the evidence changes. Several processes may have overlapped.
Climate. Some studies suggest the monsoon weakened around this time, reducing rainfall in parts of the region. Some researchers link this to a widespread dry episode in the ancient world around 2200 BCE, but how far it affected the Indus region, and how quickly, is debated.
Rivers. The Ghaggar-Hakra system seems to have lost reliable flow, probably because of shifts in river sources and rainfall, leaving many settlements without a dependable supply. A study published in 2012 argued that monsoon-fed rivers in the east were vulnerable to weaker rains. Other river changes, including floods and channel shifts on the Indus, may have damaged some places.
Trade. Contact with Mesopotamia appears to decline around 1900 BCE, partly because of changes in the Gulf and Mesopotamian trading systems. Reduced overseas demand may have hurt craft production, though trade was probably only one part of the economy.
Local pressures. Evidence of disease, changing farming practice or social tension has been suggested for individual sites, but the evidence is thin and uneven.
Stage five: dispersal
By about 1900 to 1800 BCE many of the large cities were much smaller or abandoned, though a few places such as Dholavira and Harappa continued at reduced scale for some time. The script, seals and standard weights fade from the record. Meanwhile, the number of settlements in some eastern areas, such as Haryana and the Ganges-Yamuna region, and in Gujarat, increased, which suggests that people moved rather than vanished. Late Harappan villages kept farming and using many familiar crafts. Over time they merged into regional cultures of northern India.
What the evidence does not support
An older view held that invaders destroyed the Indus cities, based on skeletons at Mohenjo-Daro and on a reading of the Rigveda. Reexamination showed the skeletons did not indicate a single massacre, and the invasion story is no longer accepted. The reality seems closer to a gradual change.
It also helps to avoid a simple “collapse” narrative. Unlike the debated Classic Maya collapse, where a drought and political fragmentation are often discussed together, the Indus story combines changes in cities and economy with continued rural life. Most Indus decline theories now combine climate, rivers, trade and local factors, and they differ in which they emphasise.
Limits of the timeline
The dates depend on radiocarbon dating and pottery sequences, and many sites were excavated long ago with weaker methods. Climate records come from distant sources such as lake sediments and the sea floor, which do not always match the local conditions at a single city. For these reasons, the story above is the best present summary rather than a settled account, and it may be revised as new samples are studied.