"The most exhaustive, multi-year geological study on the the possible reasons for the decline of the Harappan Civilization was published in a 2012 paper titled 'Fluvial Landscapes of the Harappan Civilization' which identified a clear cause: a prolonged drought that ultimately made monsoonal rivers go dry or become seasonal, affecting habitability along their courses. To quote: 'Hydroclimatic stress increased the vulnerability of agricultural production supporting Harappan urbanism, leading to settlement downsizing, diversification of crops and a drastic increase in settlements in the moister monsoon regions of the upper Punjab, Haryana and Uttar Pradesh.'"

“So in hindsight, it looks like the British archaeologist and director general of the Archaeological Survey of India between 1944 and 1948, Sir Robert Eric Mortimer Wheeler, blamed the wrong person for the disappearance of the Harappan Civilization when he wrote, ‘On circumstantial evidence, Indra stands accused!’ He was suggesting, of course, that ‘invading Aryans’ had destroyed the Harappan Civilization – something for which there is no archaeological evidence.”

“The millennium or so that followed the dimming of the Harappan Civilization would have been the most tumultuous and turbulent period in the history of the modern human in south Asia. But we have very little record of this and hence very little understanding of it. Look at all that happened: a long-standing civilization, the largest of its kind at the time, fell apart due to the ravages of a long drought, and its most visible symbols of power and prestige slowly disappeared even as urbanism itself did; people migrated to the east and the south in search of a new life; a new set of migrants came in from the north-west, bringing new languages and a different culture that put emphasis on sacrificial rituals and prioritized pastoralism and cattle breeding over urban settlements; another set of migrants came in from the north-east, bringing new languages, new domesticated plants and perhaps wetland farming techniques and a new variety of rice... and thus the pot of Indian culture was put on the boil. Four thousand years later, it is still simmering, with new ingredients getting added once in a while, from the Jews to the Syrians to the Parsis.”

“The residents of Mehrgarh who raised the first mud-brick homes of two or three rooms may not have realized it then, but they were laying the foundation for the first efflorescence of civilization in South Asia, called the Harappan Civilization, or the Indus Valley Civilization. It took about 4500 years or over 150 generations, for those humble mud-brick abodes to turn into the urban structures of a Harappa or a Mohenjo-daro or a Dholavira and there must have been many twists and turns along the way. But once agriculture took root, and modern humans started creating a surplus that they could save and invest, the wheels of history started spinning fast - which would, of course, lead to the invention of the wheel itself!”

“So here is a question: if you were to identify a single person who embodies us Indians the best, who do you think it should be? Ideally, it should be a tribal woman because she is most likely to be carrying the deepest-rooted and widest-spread mtDNA lineage in India today, M2. In a genetic sense, she would represent all of our history, with very little left out. She shares the most with the largest number of Indians, no matter where in the social ladder they stand, what language they speak and which region they inhabit because we all migrants and we are all mixed. And she was here from the beginning. And she was most likely also at Mohenjo-daro as the 'dancing girl' about 4500 years ago, during the period that most shaped us as we are today.”

“No human community is of exceptional status relative to others. None are children of God, or chosen people, unless all are. And none of us live upon the centre of the earth more than we live on its periphery, since we live on the surface of a globe. Nations as we understand them today are no older than a few centuries, and we are all interconnected - genetically, culturally and historically - far more than we imagine. And even 'time immemorial', it turns out, can increasingly be pinned down, dated, analysed and grasped. And when we do that, we get a far better understanding of our society and culture, and what went into their making.”

“The best way we can define ourselves is as a multi-source civilization, not a single-source one, drawing its cultural impulses, its traditions and its practices from a variety of heredities and migration histories. The Out of Africa migrants, the fearless pioneering explorers who reached this land around sixty-five millennia ago and whose lineages still form the bedrock of our population; those who arrived from West Asia and contributed to the agricultural revolution and the building of the Harappan Civilization which then became the crucible for new practices, concepts and the Dravidian languages that enrich much of our culture today; those who came from east Asia, bringing with them new languages and plants and farming techniques; and those who migrated here from central Asia, carrying an early version of what would become a great language, Sanskrit, and all its associated beliefs and practices that have reshaped our society in fundamental ways; and those who came even later seeking refuge or for conquest or for trade, and then chose to stay - all have mingled and contributed to this civilization we call Indian. We are all Indians. And we are all migrants.”