The Rongorongo script is an undeciphered writing system used on Easter Island during the 19th century. It is believed to have been used by the Rapa Nui people, and is the only known writing system in the region. The script is written on wooden tablets,
From Wikipedia
Rongorongo is a system of glyphs discovered in the 19th century on Easter Island that has the appearance of writing or proto-writing. Numerous attempts at decipherment have been made, but none have been successful. Although some calendrical and what might prove to be genealogical information has been identified, none of the glyphs can actually be read. If rongorongo does prove to be writing and to be an independent invention, it would be one of very few inventions of writing in human history.