Isthmian script in the context of "Maya script"

Many undeciphered writing systems exist today; most date back several thousand years, although 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 (such as in the case of Vinča) 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 (unless otherwise specified).

Mesoamerica, along with Mesopotamia and China, is one of three known places in the world where writing is thought to have developed independently. Mesoamerican scripts deciphered to date are a combination of logographic and syllabic systems. They are often called hieroglyphs due to the iconic shapes of many of the glyphs, a pattern superficially similar to Egyptian hieroglyphs. Fifteen distinct writing systems have been identified in pre-Columbian Mesoamerica, many from a single inscription. The limits of archaeological dating methods make it difficult to establish which was the earliest and hence the progenitor from which the others developed. The best documented and deciphered Mesoamerican writing system, and the most widely known, is the classic Maya script. Earlier scripts with poorer and varying levels of decipherment include the Olmec hieroglyphs, the Zapotec script, and the Isthmian script, all of which date back to the 1st millennium BC. An extensive Mesoamerican literature has been conserved, partly in indigenous scripts and partly in postconquest transcriptions in the Latin script.

After the Spanish conquest of the Aztec Empire in 1521, Spanish colonial authorities and Catholic Church missionaries aimed to purge indigenous culture, religion and traditional institutions, which included the destruction of texts of Mesoamerican and pre-Columbian origin. However, some Mesoamerican texts were spared, particularly from the Yucatán of southern Mexico, recording the languages of the area. These surviving texts give anthropologists and historians valuable insight into the origins of Mesoamerican languages, culture, religion, and government. Languages recorded in Mesoamerican writing include Classical Maya, Classical Nahuatl, Zapotec, Mixtec, and various other languages, particularly of the Oto-Manguean and Uto-Aztecan families.

Olmec hieroglyphs are a set of glyphs developed within the Olmec culture. The Olmecs were the earliest known major Mesoamerican civilization, flourishing during the formative period (1500–400 BCE) in the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. The subsequent Epi-Olmec culture (300 BCE to 250 CE), was a successor culture to the Olmec and featured the Isthmian script, which has been characterized as a full-fledged writing system, though with its partial decipherment being disputed.

There is no scholarly consensus whether Olmec hieroglyphs represent language, or are a system of proto-writing; the possible existence of writing during Middle and Late Olmec periods has been a matter of long-standing debate. Direct evidence includes the appearance of individual (potential) glyphs as well as the singleton Cascajal Block that bears a potential text. Indirect evidence includes similarities in calendar and writing systems between subsequent Mesoamerican cultures, for which the Olmecs are sometimes considered a mother culture.

The Epi-Olmec culture was a cultural area in the central region of the present-day Mexican state of Veracruz. Concentrated in the Papaloapan River basin, a culture that existed during the Late Formative period, from roughly 300 BCE to roughly 250 CE. Epi-Olmec was a successor culture to the Olmec, hence the prefix "epi-" or "post-". Although Epi-Olmec did not attain the far-reaching achievements of that earlier culture, it did realize, with its sophisticated calendrics and writing system, a level of cultural complexity unknown to the Olmecs.

Tres Zapotes and eventually Cerro de las Mesas were the largest Epi-Olmec centers though neither would reach the size and importance of the great Olmec cities before them nor El Tajín after them. Other Epi-Olmec sites of note include El Mesón, Lerdo de Tejada, La Mojarra, Bezuapan, and Chuniapan de Abajo.