Back in the 19th century, eastern India was separated from the west by an impenetrable belt of trees made up of mostly thorny plants such as the Indian plum and prickly pear, as well as bamboos and babool trees. They formed a man-made barrier, more than a thousand kilometers long, that snaked all the way from Layyah in Punjab (now in Pakistan) to Burhanpur, on the banks of Narmada.

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