They have connected the dots between the growth and decline of Dholavira, the most spectacular and largest excavated Harappan city in India located in the Rann with the fate of this river which resembles the mythical Himalayan River Saraswati.
The study has just been published online in the prestigious Wiley Journal of Quaternary Science, an IIT Kharagpur release said on Thursday.
Studies made so far have been indirect attempts to trace the river's course and its connection to climate and civilization in areas far away from these ancient cities.
The research team from IIT Kharagpur, the Archaeological Survey of India (ASI), Deccan College Pune, Physical Research laboratory (PRL) Ahmedabad and the Gujarat Department of Culture, dated the archaeological remains from all the historical stages and also inferred climate shifts through time which led to the rise and fall of the Harappan city.
"Our data suggest that prolific mangroves grew around the Rann and distributaries of Indus or other palaeochannels dumped water in the Rann near southern margin of Thar Desert. This is the first direct evidence of glacial-fed rivers, quite like the supposedly mythological Saraswati, in the vicinity of Rann" said IIT Kharagpur Professor Anindya Sarkar, who led the research.
Ravi Bhushan and Navin Juyal from PRL Ahmedabad dated the carbonates from human bangles, fish otolith and molluscan shells with an accelerator mass spectrometer and found that the site was occupied from 5,500 years ago (pre-Harappan) up to 3,800 years back (late Harappan).
The Dholavirans were probably the original inhabitants in the region and had a fairly advanced level of culture even at its earliest stage. They built a spectacularcity and survived for nearly 1700 years by adopting water conservation, suggested the researchers.
The study indicates that the city expanded till 4,400 years ago followed by an abrupt decline nearly 4000 years back, at the onset of the newly-proposed Meghalayan geological stage.
ASI Researchers R.S. Bisht and Y.S. Rawat, who originally excavated the site came to the conclusion based on the degeneration of architecture, craftsmanship, and material culture.
Arati Deshpande Mukherjee of Deccan College pointed to the climate evidence coming from high resolution oxygen isotopes in snail shells - 'Terebralia palustris' - which typically grow in mangroves and was a source of food for the Dholavirans.
The lead author of the paper and a PhD student at IIT Kharagpur, Torsa Sengupta, said: "The early to mature Harappan snail isotopes suggested that the mangrove was fed by glacier river debouching in the Rann of Kutch. However, during the late Harappan period, the meltwater contribution and seasonality reduced, coinciding with the fall of Dholavira."
"Though the Dholavirans adopted excellent water conservation strategies by building dams, reservoirs and pipelines, they were pushed to the limit by a catastrophic Meghalayan mega-drought collapsing the city. Indeed, Dholavira presents a classic case for understanding how climate change can increase future drought risk as predicted by the IPCC working group" Sarkar said.
The research indicates that the collapse of Harappan Dholavira was near-synchronous to the decline at all the Harappan sites in India, as well as the societal collapse of Mesopotamia, Greece, China and the Old Kingdom of Egypt.
"This was due to the disruption of the westerlies and Indian and East Asian monsoons 4,200 years back leading to a widespread drought. The collapse of Dholavira is a very important evidence for reconstructing these global archaeological and climate events" said Mike Walker of University of Wales who discovered the Meghalayan Stage.
( With inputs from IANS )