In ancient time books were written (not typed, not printed). As a tool to write on mostly 'Bhojpatra", "Tadpatra'-leaf of a palm tree, and hand-made paper was used. Bhojpatras were available in the Himalayan regions and so were used more in these regions. Tadpatras were easily available in the regions near sea-shore and the tradition of writing remained more in vogue.
There are two peculiarities of books written on palm tree leaves. Books on palm tree leaves were written either by inscribing on it or with ink. And keeping palm tree leaves one on the other a hole was made in the centre, a thread was passed through it and wrapping it on all four sides a knot was tied and that was known as a book a work.