My home town is only 30 km from “Matale Aluvihara” where Pali cannon was written. If you go there you can get them to write something in palm leaves. My birth certificate was written in a palm leaf and lost after 30 years. They last for hundreds of years. If you are looking for oldest Buddhist script still remain you have to go to London library where there is a copy of world oldest printed book – Diamond Sutra.
A copy of the Diamond Sutra is the world’s oldest surviving printed book which is a historical document describing how Buddha explains the concept of Anatta to his disciples.http://www.diamond-sutra.com/diamond_su ... ation.html