Ans.

Proposed theories regarding the decline of the Harappan Civilization :

Definite reason that led to the decline of the Indus Valley Civilization is not known, as no reliable resource of that period is available at present. Every conclusion regarding the decline is based upon speculations of historians. Though the reason of the decline is not known, but through excavations it is clear that fall of the Harappan Civilization occurred between 1800 BC to 1700 BC.

It is commonly believed that the Aryans were the next settlers. They were skilled fighters, so their attack might have led to the destruction of the Harappan Civilization. Even the epics of the Aryans mentioned about their victory over the great cities. The human remains found during excavation of Indus valley point towards some violent cause of their death. Now many historians, who do not believe this theory, say that the Aryans might not be involved in any such attack.

Owing to this conflict, the theory of a huge climatic change or natural disaster gained credibility. It has been found out that around 2000 BC some major climatic changes started occurring in the Indus Valley. These changes had led to floods in the plains and cities. Historians have found evidence to prove this theory as well. Most of the cities in the Harappan Civilization have been found in a condition as if these had been first abandoned and then rebuilt.

Cities, for instance, were initially built with great care but reconstruction of the same was done with broken bricks and no attention was paid to the proper sewage system during reconstruction. Proper sewage system was one of the major characteristics of the Indus Valley Civilization.

Then, there was a fall in the average rainfall in the cities leading to the formation of desert-like condition. This led to the decline in agriculture on which most of the trade was dependent. Owing to this, people of the Indus Valley started shifting to some other location leading to the decline in the entire civilization. As per some scholars, the reason of the decline is the change in the course of River Ghaggar-Harka that had led to an increase in aridity of the place. Around 2000 BC, there was found an increase in arid conditions. The location where the Indus valley civilisation once flourished is a desert today.

Many theories have been formulated and provided, but all the theories met with one or another form of criticism. Archeological evidences do prove that there was no sudden collapse of the Indus Valley Civilization but it declined over a period of time and got mingled with other civilizations of that period.