Undeciphered writing systems

Many undeciphered writing systems date from several thousand years BC, though some more modern examples do exist. 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 (such as in the case of Vinča) from the question of whether the symbols actually constitute a writing system at all. Some writers have claimed to have managed to decipher certain writing systems, such as those of Epi-Olmec, Phaistos and Indus texts, but these claims have not been confirmed by independent researchers.

Proto-writing

Certain forms of proto-writing remain undeciphered and, due to a lack of evidence and linguistic descendants, it is quite likely that these writing systems will never be deciphered.

*Jiahu Script -Peiligang culture, from the 7th millennium BC.
*Vinča script, Neolithic Europe, from the 6th millennium BC.
*Banpo Script -Yangshao culture, from the 5th millennium BC.

Bronze Age scripts

The following is a list of undeciphered scripts from the Bronze Age (3300 to 1200 BC).
*Indus script — Indus Valley Civilization, from ca. 3300 BC, likely proto-writing.
*Proto-Elamite — Elam, from ca. 3200 BC.
*Linear Elamite, from ca. 2200 BC.
*Linear A — Minoan, from ca. 1900 BC, a syllabary.
*Cretan hieroglyphs - from ca. 1900 BC.
*Wadi el-Ħôl script, ca. 1800 BC, likely an abjad.
*Byblos — the city of Byblos, ca. 1700 BC.
*Phaistos Disc, ca. 1600 BC, a unique text found on one single object.
*Cypro-Minoan syllabary, from ca. 1500 BC.

Mesoamerican scripts

Many Mesoamerican writing systems have been discovered by archaeologists. Few of them have been deciphered due to a lack of knowledge of the original language. These writing systems were used between 1000 BC and 1500 AD.
*Olmec — Olmec civilization, ca. 900 BC, possibly the oldest Mesoamerican script.
*Isthmian, ca. 500 BC, apparently logosyllabic.
*Zapotec — Zapotec, ca. 500 BC.
*Mixtec — Mixtec, 14th century, perhaps pictographic.
*Quipu — Inca Empire, 15th century, is thought by some to have been a writing system, but is generally believed to be an accounting system.

Other undeciphered writing systems

*Asemic writing
*Codex Seraphinianus. Fictional.
*Khitan small script — Khitan, 10th century.
*Singapore Stone, a fragment of a sandstone slab inscribed with an ancient Southeast Asian script, perhaps Old Javanese or Sanskrit. At least 13th century, and possibly as early as 10th to 11th century.
*Voynich manuscript, before 1520. Possibly a hoax.
*Rohonc Codex, before 1838.
*Rongorongo — Rapa Nui, before 1860.