Birch bark manuscript

"Sringaverapura is a site on the bank of the Ganga, not far upstream of Allahabad. Birch leaf fragments have been identified in its Black-and-Red Ware level dated around 800 BC at the site. The nearest source of birch leaf (Betula utilis or bhurja patra) is the Himalayas, possibly Garhwal hills. What is the point in importing these leaves to Srinagaverapura unless they were used for writing? This is certainly a piece of hard circumstantial evidence in favour of pre-Asokan existence of writing in early historic India."