The most exhaustive, multi-year geological study on the the possible reasons for the decline of the Harappan Civilization was published in a 2012 pap… - Tony Joseph

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' (the image on the cover) about 4500 years ago, during the period that most shaped us as we are today.

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.

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.