Palm leaf manuscripts (Tamil: ஓலைச் சுவடி, Oriya: ତାଳପତ୍ର ପୋଥି, Kannada: ತಾಳೆಗರಿ, Sinhala: පුස්කොළ ලෙඛන, Javanese: rontal, Indonesian: lontar) are manuscripts made out of dried palm leaves. They served as the paper of the ancient world in parts of Asia as far back as the 5th century BCE. and possibly much earlier. They were used to record actual and mythical narratives in South Asia and in South East Asia. Initially knowledge was passed down orally, but after the invention of alphabets and their diffusion throughout South Asia, people eventually began to write it down in dried and smoke treated palm leaves of Palmyra palm or talipot palm.
An article on some undeciphered palm leaf manuscripts is here