Aridification of this region during the 3rd millennium BCE may have been the initial spur for the urbanisation associated with the civilisation, but eventually also reduced the water supply enough to cause the civilisation's demise, and to scatter its population eastward.
Inhabitants of the ancient Indus river valley developed new techniques in handicraft (carnelian products, seal carving) and metallurgy (copper, bronze, lead, and tin).
The Indus cities are noted for their urban planning, baked brick houses, elaborate drainage systems, water supply systems, and clusters of large non-residential buildings.
Excavated ruins of Mohenjo-daro, Sindh province, Pakistan, showing the Great Bath in the foreground.
Mohenjo-daro, on the right bank of the Indus River, is a UNESCO World Heritage Site, the first site in South Asia to so declared.
The Indus Valley Civilisation (IVC) was a Bronze Age civilisation (3300–1300 BCE; mature period 2600–1900 BCE) mainly in the northwestern regions of South Asia, extending from what today is northeast Afghanistan to Pakistan and northwest India.
It flourished in the basins of the Indus River, which flows through the length of Pakistan, and along a system of perennial, mostly monsoon-fed, rivers that once coursed in the vicinity of the seasonal Ghaggar-Hakra river in northwest India and eastern Pakistan.
There were earlier and later cultures, often called Early Harappan and Late Harappan, in the same area of the Harappan Civilisation.
The Harappan civilisation is sometimes called the Mature Harappan culture to distinguish it from these cultures.
As of 1999, over 1,056 cities and settlements had been found, of which 96 have been excavated, mainly in the general region of the Indus and Ghaggar-Hakra Rivers and their tributaries.
Among the settlements were the major urban centres of Harappa, Mohenjo-daro (UNESCO World Heritage Site), Ganeriwala in modern-day Pakistan; and Dholavira, Lothal, Rupar, Kalibangan and Rakhigarhi in present-day India.
The Harappan language is not directly attested and its affiliation is uncertain since the Indus script is still undeciphered.
A relationship with the Dravidian or Elamo-Dravidian language family is favoured by a section of scholars.
The ruins of Harappa were first described in 1842 by Charles Masson in his Narrative of Various Journeys in Balochistan, Afghanistan, and the Punjab, where locals talked of an ancient city extending "thirteen cosses" (about 25 miles), but no archaeological interest would attach to this for nearly a century.