 They cite various reasons including the lack of attestation of rongorongo prior to the 1860s, the clearly more recent provenance of some of the tablets, the lack of antecedents, and the lack of additional archaeological evidence since its discovery.Others argue that it was merely a mnemonic list of symbols meant to guide incantations.Whether rongorongo is merely an example of trans-cultural diffusion, or a true indigenous Austronesian writing system (and one of the few independent inventions of writing in human history) remains unknown and may never be known.