The earliest traces of civilization in the Indian subcontinent are to be found in places along, or close, to the Indus river. Excavations first conducted in 1921-22, in the ancient cities of Harappa andMohenjodaro, both now in Pakistan, pointed to a highly complex civilization that first developed some 4,500-5,000 years ago, and subsequent archaeological and historical research has now furnished us with a more detailed picture of the Indus Valley Civilization and its inhabitants. The Indus Valley people were most likely Dravidians, who may have been pushed down into south India when the Aryans, with their more advanced military technology, commenced their migrations to India around 2,000 BCE. Though the Indus Valley script remains undeciphered down to the present day, the numerous seals discovered during the excavations, as well as statuary and pottery, not to mention the ruins of numerous Indus Valley cities, have enabled scholars to construct a reasonably plausible account of the Indus Valley Civilization.
Some kind of centralized state, and certainly fairly extensive town planning, is suggested by the layout of the great cities of Harappa and Mohenjodaro. The same kind of burnt brick appears to have been used in the construction of buildings in cities that were as much as several hundred miles apart. The weights and measures show a very considerable regularity. The Indus Valley people domesticated animals, and harvested various crops, such as cotton, sesame, peas, barley, and cotton. They may also have been a sea-faring people, and it is rather interesting that Indus Valley seals have been dug up in such places as Sumer. In most respects, the Indus Valley Civilization appears to have been urban, defying both the predominant idea of India as an eternally and essentially agricultural civilization, as well as the notion that the change from ‘rural’ to ‘urban’ represents something of a logical progression. The Indus Valley people had a merchant class that, evidence suggests, engaged in extensive trading.
The Indus Valley civilization raises a great many, largely unresolved, questions. Why did this civilization, considering its sophistication, not spread beyond the Indus Valley? In general, the area where the Indus valley cities developed is arid, and one can surmise that urban development took place along a river that flew through a virtual desert. The Indus Valley people did not develop agriculture on any large scale, and consequently did not have to clear away a heavy growth of forest. Nor did they have the technology for that, since they were confined to using bronze or stone implements. They did not practice canal irrigation and did not have the heavy plough. Most significantly, under what circumstances did the Indus Valley cities undergo a decline? The first attacks on outlying villages by Aryans appear to have taken place around 2,000 BCE near Baluchistan, and of the major cities, at least Harappa was quite likely over-run by the Aryans. In the Rig Veda there is mention of a Vedic war god, Indra, destroying some forts and citadels, which could have included Harappa and some other Indus Valley cities. The conventional historical narrative speaks of a cataclysmic blow that struck the Indus Valley Civilization around 1,600 BCE, but that would not explain why settlements at a distance of several hundred miles from each other were all eradicated. The most compelling historical narrative still suggests that the demise and eventual disappearance of the Indus Valley Civilization, which owed something to internal decline, nonetheless was facilitated by the arrival in India of the Aryans.