The Indus Valley Civilisation is also known as the Harappan Civilisation after the city of Harappa where it was first discovered. It extended over a large region of present-day Pakistan and western India.
It was one of the earliest known "state societies", existing as a unified culture between approximately 2600 BC and 1900 BC. Over 1000 settlements have been found, the majority along the Ghaggar-Hakra river. Others were on the Indus and its tributaries or spread as widely as Mumbai (Bombay) to the south, Delhi to the east, the Iranian border to the west and the Himalayas to the north.
The Indus civilisation was predated by the first farming settlements in south Asia to the west in Balochistan, of which the earliest is Mehrgarh, established around 6500 BC. Pottery was in use by around 5500 BC. The Indus civilisation grew out of later settlements in Sindh and Punjab. Some of the settlements grew into cities and show a unified cuture from around 2600 BC, around which time new settlements were founded and many of the Balochistan settlements were abandoned. The total population has been estimated at 5,000,000.
There was extensive trade, including by boat. There was trade with the Mesopotamians, who probably knew the Indus Valley as Meluhha. Materials from distant regions were used in the cities for constructing seals, beads and other objects. The seals have images of animals, gods etc., and inscriptions. Some of the seals were used to stamp clay on trade goods, but they probably had other uses. The cities had large structures and elaborate drainage systems. A system of uniform weights and measures was in use.
A pictograph script was used for writing, which has not been deciphered despite numerous attempts. Most of the inscriptions have been found on seals and pottery and are no more than 4 or 5 characters. About 400 or more symbols have been identified. It was usually read from right to left. Early examples of a few symbols have been found on pottery dating before 3000 BC. There is no evidence of a large body of literature and it's not known which language the writing represents: it's now usually assumed to be in the Dravidian family although Indo-Aryan and Sumerian have also been proposed.
After 1900 BC, trade seems to have reduced and the cultural unification was fragmented into smaller regions. Harappa became part of the Cemetery H culture. The script seems to have disappeared around 1500 BC. A major geographical influence around this time was the gradual drying up of the Ghaggar-Hakra river, possibly caused by the shifting of rivers after earthquakes. The population from around the river dispersed to neighbouring regions.
The relationship between the Indus civilisation and the early Sanskrit language culture that produced the Vedic texts of Hinduism is unclear. On the one hand, the Vedic texts constantly refer to the horse and chariot, but the Indus civilisation was an urban and trade culture in which there is no evidence for the use or knowledge of the horse. On the other hand, the Vedas refer to a river Sarasvati which is often identified as the Ghaggar-Hakra river before it dried up. Various resolutions have been suggested, e.g., that the early Vedas refer to a different river and were taken to India during an Aryan migration or invasion.
- http://www.harappa.com/ has descriptions and photographs of archaeological excavations.
- http://www.safarmer.com/frontline/ shows how the Indus Valley Civilisation has become contentious in present-day Indian politics, giving a summary of present knowledge.