Any account of history leaves a reader with the impression that every word has the weight of gospel. But that is deceptive as history depends entirely on source material. Until relatively recently that was a collection of contemporary texts, on paper, parchment or stone. Thus, we know about the greatness of Ashoka or the wickedness of Aurangzeb only through the written records of their times Histories have to be updated as and when new materials turn up. But in the last two centuries sc