Certain forms of proto-writing remain undeciphered and, because of a lack of evidence and linguistic descendants, it is quite likely that they will never be deciphered.
Other areas
Virtually all Mesoamerican Glyphic Scripts remain undeciphered, with the only exceptions being Lowland Maya Hieroglyphs and Mixteca-Puebla Hieroglyphs (represented by several regional glyphic traditions used in the whole of Postclassic Mesoamerica outside the Maya Lowlands, the most well known of which are the Aztec Script and the Mixtec Script). All Mesoamerican writing systems are thought by linguist Alfonso Lacadena (Lacadena 2012) to descend from Olmec Glyphs, with it splitting in the Late Formative into three branches: Epi-olmec, Zapotec and Central Mexican (from this branch would eventually emerge the Teotihuacan Glyphic Script).
One very similar concept is that of false writing systems, which appear to be writing but are not. False writing cannot be deciphered because it has no semantic meaning. These particularly include asemic writing created for artistic purposes. One prominent example is the Codex Seraphinianus.
Another similar concept is that of undeciphered cryptograms, or cipher messages. These are not writing systems per se, but a disguised form of another text. Of course any cryptogram is intended to be undecipherable by anyone except the intended recipient so vast numbers of these exist, but a few examples have become famous and are listed in list of ciphertexts.
Salgarella, Ester (2022). "Linear A". In Hornblower, Simon; Spawforth, Antony; Eidinow, Esther (eds.). Oxford Classical Dictionary. Oxford University Press. doi:10.1093/acrefore/9780199381135.013.8927 (inactive 1 November 2024). ISBN 978-0-19-938113-5.{{cite encyclopedia}}: CS1 maint: DOI inactive as of November 2024 (link) 978-0-19-938113-5 ↩
[1] Meissner, T., & Steele, P., "Linear A and Linear B: Structural and contextual concerns", Edizioni Consiglio Nazionale delle Ricerche, 2017 https://api.repository.cam.ac.uk/server/api/core/bitstreams/7e3a97dd-5ae9-46e3-bab5-fdd644e45bec/content ↩
"Mysterious Voynich manuscript is genuine, scientists find". Archived from the original on 2009-12-07. Retrieved 2009-12-07. https://web.archive.org/web/20091207010237/http://www.monstersandcritics.com/news/europe/news/article_1516863.php/Mysterious-Voynich-manuscript-is-genuine-scientists-find ↩
Cacciafoco, Francesco Perono (1 September 2021). "The Undeciphered Inscription of the Baptistery of Pisa". Academia.edu. Retrieved 22 February 2024. https://www.academia.edu/51125775 ↩
Ministry of Information and National Guidance, Somalia, The writing of the Somali language: A Great Landmark in Our Revolutionary History, (Ministry of Information and National Guidance: 1974) https://books.google.com/books?id=v-GwAAAAIAAJ ↩
Arellano, Carmen. "Un khipu olvidado: el përon mapuche. Notas acerca de su función". Academia.edu. https://www.academia.edu/11320388 ↩
"Unraveling an Ancient Code Written in Strings". Sapiens. 2017-11-07. Retrieved 2024-06-29. https://www.sapiens.org/language/khipu-andean-writing/ ↩
Uriarte, María Teresa (2018). Olmecas (in Spanish). Universidad Nacional Autónoma de México. ISBN 978-88-16-60514-5. 978-88-16-60514-5 ↩
Pool, Christopher (2007-02-26). Olmec Archaeology and Early Mesoamerica. Cambridge University Press. ISBN 978-0-521-78312-5. 978-0-521-78312-5 ↩
Peregrine, Peter N.; Ember, Melvin (2012-12-06). Encyclopedia of Prehistory: Volume 5: Middle America. Springer Science & Business Media. ISBN 978-1-4615-0525-9. 978-1-4615-0525-9 ↩
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Clemmensen, Mikkel Bøg; Helmke, Christophe (2023-06-08). Western Mesoamerican Calendars and Writing Systems: Proceedings of the Copenhagen Roundtable. Archaeopress Publishing Ltd. ISBN 978-1-80327-486-7. 978-1-80327-486-7 ↩