An undeciphered writing system is a written form of language that is not currently understood. Many undeciphered writing systems date from several thousand years BC, though some more modern examples do exist. The term "writing systems" is used here loosely to refer to groups of glyphs which appear to have representational symbolic meaning, but which may include "systems" that are largely artistic in nature and are thus not examples of actual writing. The difficulty in deciphering these systems can arise from a lack of known language descendants or from the languages being entirely isolated, from insufficient examples of text having been found and even from the question of whether the symbols actually constitute a writing system at all. Some researchers have claimed to be able to decipher certain writing systems, such as those of Epi-Olmec, Phaistos and Indus texts; but to date, these claims have not been widely accepted within the scientific community, or confirmed by independent researchers, for the writing systems listed here.
Proto-writing
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.
*Linear A and Cretan hieroglyphs are both believed to be an example of the Minoan language. Several words have been decoded from the scripts, but no definite conclusions on the meanings of the words have been made.
Para-Lydian script, known from a single inscription found in Sardis Synagogue, c. 400–350 BC.
Sidetic script – Asia Minor, c. 5th to 3rd centuries BC.
Tujia script
Shankhalipi
Late Harappan script
Vikramkhol inscription
Mesoamerican scripts
Many Mesoamerican writing systems have been discovered by archaeologists. Many of them remain undeciphered due to a lack of knowledge of the original language. These writing systems were used between 1000 BC and 1500 AD.
Mixtec – Mixtec, 14th century, perhaps pictographic. Many of the pictographic elements of the script are well-understood, but semantic and linguistic components are less well known.
South American scripts
Quipu – Inca Empire, 15th century, thought by some to have been a writing system, but generally believed to be an accounting system.
Ancient inscriptions in Somalia, According to the Ministry of Information and National Guidance of Somalia, inscriptions can be found on various old Taalo Tiiriyaad structures. These are enormous stone mounds found especially in northeastern Somalia. Among the main sites where these Taalo are located are Xabaalo Ambiyad in Alula District, Baar Madhere in Beledweyne District, and Harti Yimid in Las Anod District.
Voynich manuscript, carbon dated to the 15th century.
The Newton Stone, which is considered by many scholars to be modern forgery
Some scholars consider the corpus of Pictish symbol stones to be an undeciphered writing system
So-called Hamptonese, a language used by outsider artist James Hampton in his presumably religious text.
Related concepts: texts that are not writing systems
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 the :Category:Undeciphered historical codes and ciphers|undeciphered historical codes and ciphers category.
