Indus Valley Civilisation

What happened c. 1500 BCE?

Around 1900 BC, signs of a gradual decline begin to emerge. People started to leave the cities. Those who remained were poorly nourished. By around 1800 BC, most of the cities were abandoned.

In the aftermath of the Indus civilization's collapse, regional cultures emerged, to varying degrees showing the influence of the Indus civilization. In the formerly great city of Harappa, burials have been found that correspond to a regional culture called the Cemetery H culture. At the same time, the Ochre Coloured Pottery culture expands from Rajasthan into the Gangetic Plain.

It is in this context of the aftermath of a civilization's collapse that the Indo-Aryan migration hypothesis into northern India is discussed. In the early twentieth century, this migration was forwarded in the guise of an "Aryan invasion", and when the civilization was discovered in the 1920s, its collapse at precisely the time of the conjectured invasion was seen as an independent confirmation.

In the words of the archaeologist Mortimer Wheeler, the Indo-Aryan war god Indra "stands accused" of the destruction. It is however far from certain whether the collapse of the IVC is a result of an Indo-Aryan migration, if there was one. It seems rather likely that, to the contrary, the hypothized Indo-Aryan migration was as a result of the collapse, comparable with the decline of the Roman Empire and the incursions of relatively primitive peoples during the Migrations Period.

A third possibilty is that IVC colapsed primarily due to natural reasons (climate change, tectonic activity along the subduction zone along the Indo-Asian plate boundary) and that there was no Indo-Aryan invasion that took place. Swastika, a symbol associated with the Indo-Aryans by easrly historians, has been found in large numbers over several IVC sites.

Similarly, several Shiv Lingum type structures have been found at several IVC sites. Both the Swastika and Shiv Lingum have been symbols closely related to the Hindu religion (even to the present day), indicating continuity of the IVC civilization rather than a complete collapse or destruction. The discovery of Swastikas have put to question the theory of an Aryan invasion of Indian subcontinent.A possible natural reason of the IVC's decline is connected with climate change.

In 2600 BC, the Indus Valley was verdant, forested, and teeming with wildlife. It was wetter, too; floods were a problem and appear, on more than one occasion, to have overwhelmed certain settlements. As a result, Indus civilization people supplemented their diet with hunting. By 1800 BC, the climate is known to have changed. It became significantly cooler and drier.

The crucial factor may have been the disappearance of substantial portions of the Ghaggar-Hakra river system. A tectonic event may have diverted the system's sources toward the Ganges Plain, though there is some uncertainty about the date of this event. Such a statement may seem dubious if one does not realize that the transition between the Indus and Gangetic plains amounts to a matter of inches.

The region in which the river's waters formerly arose is known to be geologically active, and there is evidence of major tectonic events at the time the Indus civilization collapsed. Although this particular factor is speculative, and not generally accepted, the decline of the IVC, as with any other civilization, will have been due to a combination of a variety of reasons.