The Indus Valley Civilisation (IVC) was a Bronze Age civilisation in the northwestern regions of South Asia, lasting from 3300 BCE to 1300 BCE, and in its mature form from 2600 BCE to 1900 BCE. Along with ancient Egypt and Mesopotamia it was one of three early civilisations of the region comprising North Africa, West Asia and South Asia, and of the three, the most widespread, its sites spanning an area stretching from northeast Afghanistan, through much of Pakistan, and into western and northwestern 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.
The civilisation's cities were noted for their urban planning, baked brick houses, elaborate drainage systems, water supply systems, clusters of large non-residential buildings, and new techniques in handicraft (carnelian products, seal carving) and metallurgy (copper, bronze, lead, and tin). The large cities of Mohenjo-daro and Harappa very likely grew to containing between 30,000 and 60,000 individuals, and the civilisation itself during its florescence may have contained between one and five million individuals. Gradual drying of the region's soil 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.
The Indus civilisation is also known as the Harappan Civilisation, after its type site, Harappa, the first of its sites to be excavated early in the 20th century in what was then the Punjab province of British India and now is Pakistan. The discovery of Harappa and soon afterwards Mohenjo-Daro was the culmination of work beginning in 1861 with the founding of the Archaeological Survey of India during the British Raj. There were however earlier and later cultures often called Early Harappan and Late Harappan in the same area; for this reason, the Harappan civilisation is sometimes called the Mature Harappan to distinguish it from these other cultures. By 2002, over 1,000 Mature Harappan cities and settlements had been reported, of which just under a hundred had been excavated, However, there are only 5 major urban sites: Harappa, Mohenjo-daro (UNESCO World Heritage Site), Dholavira, Ganeriwala in Cholistan, and Rakhigarhi. The early Harappan cultures were preceded by local Neolithic agricultural villages, from which the river plains were populated.
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.