Now, what has increased the excitement of Swarnkar and his team is the discovery of signs of a flood at the Purana Qila site. "Earlier excavations here have not recorded evidence of a pre-Mauryan flood," says Swarnkar as he points to a deep trench wall that shows a layer of soil abruptly changing colour from reddish brown to brownish yellow, with a soft clay-like texture. The mixture of sand and silt from the layer has been sent for dating.

Here's why this fresh discovery is important: The most prominent of Lal's findings at Purana Qila was the traces of painted grey ware (PGW) that suggests the historicity of the Mahabharata. Lal had dug up Purana Qila as part of his mission to excavate various sites mentioned in the Mahabharata. At all the other sites such as Hastinapura, Mathura, Ahichatra, Kampilya, Barnava and Kurukshetra, he had found PGW (a style of fine, grey pottery painted with geometric patterns in black) to be a common feature. The PGW was found to archaeologically belong to the 6th-12th century BC and thus, Lal associated PGW with the Mahabharata period, estimating 900 BCE as the period of the epic war.

"Each era or period in history is identified by its pottery along with associated ware or structural forms," said Swarnkar.

But it was the evidence of a flood at Hastinapur site that really cemented Lal's belief in the veracity of the ancient text. The dating showed that the flood happened around 800 BCE, which corroborates the text. Mahabharata mentions that a flood in the time of Nichakshu (the sixth ruler of Hastinapur starting from Yudhishthira) destroyed the city and forced its residents to flee, prompting the ruler to shift his capital to Kaushambi near Allahabad.