The ingenuity of our ancestors of Bronze Age is seen to be believed. Their culture known as the Neolithic culture starting from 7000 BCE with a rise in 2600 BCE and a fall in 1900 BCE are well recorded in the prehistory. It is amazing that despite no scientific background these people had immense knowledge of making alloys. These people were well off and their civilization at its peak covered an area of more than a million square kilometers. Harappans had created well developed urban dwellings, the relicts of which are a constant source of information to the archeologists.

Kavita Gangal, M.N. Vahia and R.Adhikari of Tata Institute of Fundamental Research, Centre for Excellence in Basic Science, Mumbai and Institute of Mathematical sciences, Chennai respectively studied the spatio-temporal growth of rise and fall of Harappan civilization. They found that during its peak urbanism was centered on three distinct geographical provinces, viz. Baluchistan, Gujarat and Ghaggar-Hakra valley (Rajasthan). An urban settlement takes time to grow and mature. Linguist George Kingsley Zipf proposed a mathematical law in 1935 which works out the probabilities of growth of population in any given urban centre. What surprises the researchers now is that the mature urban centres of Harappan urbanization were according the Zipfian law proposed some 5000 years later!

The vanished urban centres of Indus Valley civilization must have been awesome in reality. It was the largest of the Bronze Age civilizations say Kavita and her co-researchers. Imagine the immense expanse it occupied from Shortugai in northern Afghanistan to Daimabad in southern India and from Sutkagen Dor on Iranian border to Hulas in Uttar Pradesh. The area it covered was over a million square kilometers and was much larger that both Nile and Tigris-Euphrates riverine civilizations put together. After 1900 BCE (Before Common Era) the civilization collapsed, the show was over and it took man another 1000 years to establish urban centres in Ganga Valley. 

What were the conditions that helped Harappan urbanism grow? And what were the causes of their sudden decline? These are some of the unanswered questions which are still enigmatic. Kavita and her team searched for answers to these questions with the help of topography, groundwater conditions of those days, radiocarbon dates and archeological data and have tried to establish the pattern of urbanization in Indus Valley in terms of their space and time. They found that the earliest Neolithic sites have not shown any change over a period of 2000 years, that is from 7000 to 5000 BCE. Mehergarh, a site near the Bolan pass has been cited as an example. Mehergarh also has the earliest evidences of wheat cultivation.

After this a cluster of sites in Jamnagar region of Gujarat, Binjour, Ganganagar or Ghaggar-Hakra paleochannel giving age around 4000 BCE have been found. It is likely that the missing 1000 years between Mehergarh and these sites are still buried in the huge Indo-Gangetic alluvium! Ghaggar-Hakra site shows evidences of availability of running water. Imagine people using running water in those ancient days! This site flourished for 300 years and it is anybody’s guess that there could have been no habitation without water. While Ghaggar-Hakra region was being urbanized 800 km away in Jamnagar region a parallel urbanization was on. In other words independent urbanization was common even in those days. There could be several reasons for this pattern of development, congenial climate and availability of water must have been the prime ones! During these 300 years not only this site, but a large cluster of sites flourished along the Ghaggar-Hakra River. 

With the passage of time it appears that newer sites were developed downstream of the present site at Ghaggar-Hakra. It is quite astonishing that at the same time independent urbanization was being carried out in Gujarat. In those primitive days of probably no or very rare communication how the two sites came up at the same time is quite vexing.

The next 500 years saw development of settlements further south in the lower Indus plains-people there probably received inputs for the Baluch settlements and Ghaggar-Hakra urban centres! By 2500 BCE, the Harappan society was at its peak and had considerably matured. Dense urbanization of that period is seen around Ghaggar-Hakra and in Gujarat. For coming 600 years approximately 700 sites spread over an area of about one million square kilometers were virtually masters. It was this period which was the peak of urban planning in those days. The well laid drainage system etc of those days is far better than many of the present day’s ‘developed’ cities of India and Pakistan say the researchers. The distribution of population clearly follows the Zipf’s law say Kavita and her colleagues. What were the political reasons or source of income which lead to such beautifully planned cities is still debatable.

Around 1900 BCE the decline of Ghaggar-Hakra urban centres had set in. The reasons are still not clear. On the other hand the sites in Gujarat region do not show co-eval (at the same time) decline. It is thus conjectured that the reasons for vanishing cities of Ghaggar-Hakra region were localized. By 1500 BCE the urban areas of few sites in the Indus and most of Ghaggar-Hakra region had collapsed. While at its peak, the lower Indus region had seen upcoming of maximum centres and now at its decline again the lower Indus region was affected maximum. By 600BCE maximum Indus sites had been abandoned. 

While the researchers are still searching for answers to the question why such well developed urban areas perished? But the present trend of urban growth and climate change is a positive indicator of the crisis the Harappans must have faced. They must have faced a grave water problem. It was either excess water, that is floods or there was no drinking water left!

Our Harappan ancestors might not have been great scientists but it is certain that they knew the importance of drainage and also water storage. But when the rain god changes mind and stops sending rain drops on the sands of time, crisis begins. All animals including the humans have no option but to leave their beautifully designed urban areas and migrate to areas where water is available. Possibility of this kind of situation can not be ruled out for the Harappan urban centres.

Times have changed and we claim to have a vision. Did Harappans have a vision in 2500 BCE about what will be the situation in 1900 BCE? Do we have a vision of what will happen to New Delhi or New York in 3000 AD?