Vintage Cambodian Accordion

I found this vintage accordion book in an antique store in Saigon years ago.  I'm told it is a Camodian book of tales mixing Hindu and Buddhist stories.  It appears to be a sort of "primer" book....as if someone was learning to illustrate.  There are these beautiful traced lines and, while some of it is drawn gracefully and confidently, some of it appears a bit clumsy, with erasure marks and a sort of titanium "white-out" applied. 
I love it for all its flaws and grace. 
The calligraphy is amazing....I'm told it is Khmer.
I've never measured the length unfolded but it's about 15" in height and I would guess it might unfold to nearly 12' in length.