The Mexican state of Oaxaca was the heartland of one of the oldest and most enduring Mesoamerican polities. Between 300 BC and 700 AD, the ancient Zapotec state, centered at its capital of Monte Albán, flourished. In its long history, it not only fought and conquered many of its neighbors, but also engaged in diplomacy with the famous city of Teotihuacan. It is in these contexts that Zapotec writing is found.
Compared to other major Mesoamerican writing systems, Zapotec is still poorly understood. First of all, the underlying language itself presents a problem. The first European record of the Zapotec language dates from no earlier than the 16th century, and the ancient form of Zapotec from a thousand years earlier is not documented at all. Efforts are underway to reconstruct this "proto-Zapotec" language from the modern Zapotec languages, but such tasks take years to refine. Another factor contributing to the lack of progress in Zapotec decipherment is the relatively meager number of texts available to researchers. On top of this problem, the known texts are usually very short, no more than 10 glyphs, making it difficult to discover grammatical structures like sentences.
Mathematics and Calendrics
What we do know about Zapotec derive mostly from comparing with similar features in other Mesoamerican writing systems. Like other Mesoamerican scripts, Zapotec used the bar-and-dot notation to represent numbers. In terms of time-keeping, the Zapotecs employed the 365-day solar calendar (called yza) and the 260-day sacred calendar (called piye).
A detail explanation of the sacred calendar can be found at Mesoamerican Writing Systems, but in brief it can visualized as two interlocked cycles of 20 "day signs" and 13 numbers or "coefficients". The two cycles move in parallel, so a day with the 1st day sign and coefficient 1 will be followed by a day with the 2nd day sign and coefficient 2.
The following is a list of day signs in the piye. However, even the list of days in the piye is controversial, as nearly every published paper presents a different list. The following list is from Javier Urcid (2000).
Another cycle of time recorded on Zapotec texts is the Calendar Round, a 52-year cycle that interlocks the solar and sacred calendars. A year in the Calendar Round is identified by the date in the sacred calendar that corresponds to the first day in the solar year. Because of the way the mathematics works out, only four day signs in the piye can occur on the first day of the solar year. These four day signs are called "year bearers" because they "bear" the burden of the year. To graphically distinguish Calendar Round years from days in the piye, a special glyph in the shape of a headdress or crown is placed above the year bearer. The four year bearers are laa (lightning), china (deer), piya (soap plant), and xoo (earthquake).
It is not known if the Zapotecs counted time in other calendrical cycles such as the solar calendar or "weeks" of 13 days called trecenas. Because the coefficients of the piye can only go up to 13, any glyph compound with a numeral higher than 13 can potentially be a day in a solar month, a solar month, or a trecena. One glyph, known as the glyph W due to its similarity to the letter, not only accompany numbers larger than 13 but also occur near Calendar Round and piye dates. However, mathematical simulation has shown that glyph W cannot form part of any of these three possibilities. Glyph W definitely plays a time-keeping role, but right now it's an enigma.
Unlike later Mixtec and Aztec scripts, Zapotec was much more textual, possibly capable of representing sentences. Zapotec very well could be a logophonetic writing system, but likely not as extensively phonetic as Epi-Olmec or Maya. For instance, the number of non-calendrical glyphs range between 80 to 90, making it possible that Zapotec contained a mixture of logograms and phonograms. Also, the way signs are joined into compounds might indicate affixes, possibly spelled out phonetically, attached to a root logogram to form a noun or verb phrase. Some tantalizing clues come from Javier Urcid, whose studies have shown that possible instances of homophonic principle, or "rebus writing", are used in naming personages. He also demonstrated that grammatical constructs (like short sentences) might be present in some monuments (which you will see below).
Historical Context of Zapotec Writing
The Zapotec script has great antiquity, being one of the earliest writing systems in Mesoamerica. The first examples of Zapotec writing are in the form of danzante slabs, stone monuments carved with the image of slain and mutilated captives and a brief inscriptions. The majority of danzantes are found in Monte Albán, but one is found in the nearby town of San José Mogote. While once the San José Mogote danzante was thought to be the most ancient Zapotec inscription (dated to 500 BC), there is now considerable argument against this date. However, regardless of the status of the San José Mogote slab, danzantes are generally dated to the period known as Monte Albán I (400 to 200 BCE), still making them the some of the earliest texts in Mesoamerica.
The texts on danzante slabs vary greatly in content, but in the simplest form an inscription consists of a day in the sacred calendar. In ancient Oaxaca, a person is named for the day in the sacred calendar he or she was born on, so it is most likely that the danzantes depict and name the slain captive. So from its inception, Zapotec writing is used as a political tool to chronicle and glorify the the military prowess of the Zapotec state.
Apart from the danzantes, there were other kinds of inscriptions. Stelae 12 and 13, which are very likely contemporary with the danzantes, not only display dates in the Calendar Round, but also show that the system is already textual because of the presence of non-calendrical signs.
Later, during the period of Monte Albán II (200 BCE to 250 CE), the military use of Zapotec writing is taken to another level. Instead of depicting slain captives, these new monuments very likely record and commemorate conquests of other polities in the Valley of Oaxaca. These monuments are called conquest slabs, and they usually contain a central vertical glyphic sequence that consists of a variable glyph, a "mountain" glyph, and an inverted head. Generally speaking, in Mesoamerica, the word "mountain" or "hill" often appear as part of place names. The inverted head could be interpreted as a defeated enemy. This leads to the conclusion that the variable glyph must be the name of the place that was conquered by the Zapotecs. An example is the following (graciously provided by David R Hixson who runs the amazing Mesoamerican Photo Archives):
By comparing the name of towns on these conquest slabs with names of towns on 15-th century Aztec manuscripts of tributes from Oaxaca, scholars have determined the size of the Monte Albán state when the slabs were made. It extended well outside the Valley of Oaxaca.
So far monuments have been anonymous. However, a set of monuments located in the South Platform of Monte Albán not only reflects the martial nature of the Zapotec state, but depicts and names what appears to be a ruler. Furthermore, by comparing this group of monuments, Javier Urcid detect a "formula" or pattern of glyphs that might be a similar sentences with variations in subjects and objects.
Images accompanying the texts on the South Platform monuments depict a ruler and bound captives, which leads to the interpretation of the glyphs (especially the "fish" and "knotted bag" glyphs) as related to glorification of the ruler by a display of his prisoners. You can see the in situ reproduction of these monuments at the Monte Albán South Platform Monuments section at the Mesoamerican Photo Archives.
However, not all texts in Monte Albán are war-related. The Lápida de Bazán is thought to represent some form of diplomatic relationship between Monte Albán and Teotihuacán. The evidence is the figure on the left appears to wearing Teotihuacán-style clothing, and every well might have been a visitor from that great city in Central Mexico. The person on the right probably was a local ruler, dressed in local jaguar-style clothing. Due to lack of calendrical signs, the accompanying text might have recorded what the depicted event was.
In addition to the Lápida de Bazán, there are many other clues about the relationship between the two metropolises in the early Classic. Some buildings in Monte Albán have Teotihuacano architectural influences. In Teotihuacán itself, there was a Zapotec barrio where a permanent Zapotec colony was established and flourished.
At its peak between 100 and 600 CE, Monte Albán had as many as 30,000 inhabitants. However, after 700 CE, the population rapidly declined, and it probably ceased to be the capital of the Zapotec state. Regional states appeared, and the Monte Albán hegemony was at its end.
The focus of writing in these new regional states shifted from warfare and diplomacy to royal lineage. Not surprisingly these new kind of monuments are called "Genealogical Registers" by archaeologists.
Genealogical registers depict notable ancestors of the patrons who commissioned the work. They are visually separated into levels, usually two, each one with a couple engaging in some kind of activity. Often the couple on one level is older than the couple in the other, depicting most probably two generations. In the above example, the top level appears to be the older generation, as the beard on the man of that level seems to indicate. The characters at the top level are Lady 3 Eye, and Lord 1 or 2 Monkey (the number is damaged, but it is either 1 or 2 given the size of the damage). The lower register depicts Lady 10 Deer, and Lord 6 Soap Plant. At the top of the register there is a jaw-like opening, nicknamed "Jaw of Heaven" by Marcus and Flannery, from which some kind of supernatural descends. This supernatural is probably an ancestor, possibly the progenitor of the lineage or some other famous ancestor.
The Zapotec system very likely was the source of the Mixtec system, which is characterized by a highly pictorial and minimal set of logograms, and by the use of the rebus principle for rough phonetic spelling of names. In fact, the Zapotec writing system started to be replaced by the early form of Mixtec script by the 10th century CE. When the Spanish conquistadores arrived in Oaxaca in the 16th century CE, the Zapotec script has long been forgotten, although the Zapotec language continues to be spoken to this date.
More information can be found in Mesoamerican Writing Systems.