The mysterious fall of the largest and oldest human civilization has baffled the researchers over the centuries. The Indus Valley Civilization spread across a large expanse of land. It is believed to have spread across India, Pakistan, Bangladesh, Afghanistan and Nepal and may be even further. Though the Egyptian and Mesopotamian civilizations are the best known civilizations, but they are in no way the largest or oldest. This civilization spread across over 386,000 square miles from the plains of the Indus River to Ganges. At its peak the civilization accounted for more than 10% of the total world’s population.
People from Harappa were technologically advanced which is evident in the toilets and bathrooms in their houses. There was city wide well-built drainage system. Harappa was a prosperous center for trade. The civilization had close trading ties with the Mesopotamians. Unlike Egyptians or Mesopotamians the society was not autocratic in nature and there was no king. It is evident from the structures found, all the houses are of same stature and there are no large palaces which could be remnants of palaces. So, there seems to be prosperity everywhere, yet unlike the Egyptian or Mesopotamian civilizations, Indus Valley civilization did not survive for millions of years. The civilization only existed for six hundred years and its prosperous cities were abandoned by 1900 BC, though modern research has found that its people continued in small communities in nearby areas. What led to the demise of such a grand civilization has still not been solved. Though there are many theories.
As per the first theory, lack of trading options was a cause for the downfall of the Indus Valley civilization. Many Harappan artifacts have been found in Mesopotamian ruins. But in about 2000 BC the number of artifacts suddenly dips in numbers. This can logically mean that there was a fall in the trade relations between Indus Valley and Mesopotamian cultures. But the fall of trading would affect certain parts of the society not the whole. Trade would be just a part of professions that people engaged. So, fall of trading relations could not lead to the demise of such a great civilization, though lack of trade might be seen as an effect of the changing conditions within the civilization.
The second theory behind the vanishing of Indus Valley civilization states that invasion by foreign forces might have caused havoc. In 1940, Mortimer Wheeler found skeletons of many men, women and children. All these bodies bore marks of injuries caused by axes or swords. These were peace loving people who were victims to an aggressive invader. The Vedas also bear witness to such an invasion. Aryans had made their way into India during the late part of the Indus Valley Civilization. Rig Veda even mentioned Indra, the war god destroying the fortresses of Dasas, the dark skinned inhabitants. But this theory has been blown away by other historians. First of all, the bodies when inspected revealed that the wounds were weeks or months before the actual death. Moreover, if there was an invasion and a subsequent massacre the bodies should have been found at a single spot, they were rather found scattered in various areas. Also where are the burned cities or fortresses or weapons that would support the theory? Some scholars believe that the description in Rig Veda is not about invasion of Aryans during Indus Valley Civilization. Scholars believe that Rig Veda was written sometime around 1500-1000 BC way after the Indus Valley Civilization ceased to exist.
As per the third theory, some researchers believe that water patterns in the area suggest Harappa was exposed to severe floods. Flooding should have always been a problem for the dwellers, but the severity increased killing a large population and forcing the survivors to shift to new locations. Indeed the hurried approach with which the people left their homes, suggests that some natural catastrophe could be a probable cause.
But think again, Japan witnesses so many floods every year, so does the Gangetic Plains. The people still continue living there with minor adjustments. It is not more water that causes inhabitable situations; it is complete lack of water. It is fabled that the mythical Saraswati River was situated beside the civilization. It was a source of water for cooking, drinking, cultivation and all other aspects of life. But researchers have found proof that there was a Teutonic shift in plates in the Himalayas that changed the course of water. Saraswati River dried up. To extend the agony, weather patterns suggest that Harappa and Mohenjodaro faced long draughts. Lack of water made the people slowly shift from this civilization.