A long-running debate over the origins of one of Mexico’s important Indigenous manuscripts has been given a scientific answer. New accelerator mass spectrometry carbon-14 dating indicates that the Aubin Tonalámatl Codex was produced before the Spanish conquest, most likely during the final years of the 15th century.Aubin Codex - Public Domain
Researchers propose 1494 as the manuscript’s most likely date of production, providing new evidence that its pictographs and divinatory imagery belong to the pre-Hispanic world rather than representing a later colonial imitation.
The findings form part of a major new volume, Tonalámatl de Aubin: New Studies on a Divinatory Codex, presented on 29 August 2026 at the International University Book Fair.
Scientific Dating Resolves a Long-Standing Debate
The new research was carried out through a collaboration between Mexico’s National Library of Anthropology and History (BNAH) and the University of Colorado Boulder.
According to Baltazar Brito Guadarrama, head of the BNAH, the radiocarbon analysis indicates that the manuscript was produced no earlier than approximately 1450. Taking the complete range of the dating results into account, researchers have identified 1494 as the most likely production year.
The study also proposes 1424 as the most likely date for the acquisition or preparation of the raw material from which the manuscript was made.
This distinction is important because the age of the material and the date when the finished codex was produced are not necessarily identical.
Brito described the scientific conclusion as significant because the evidence places the manuscript within the pre-Hispanic period.
A Religious Manuscript That May Have Been Hidden
The research provides more than a date for the codex. It also offers a possible reconstruction of its history after the Spanish conquest.
The Aubin Tonalámatl appears to have remained in circulation despite the suppression of Indigenous religious practices and manuscripts under Spanish colonial rule.
Researchers Gerardo Gutiérrez and William Taylor, working with Brito, examined the manuscript using accelerator mass spectrometry carbon-14 dating. In their study, they suggest that the codex may have been deliberately concealed between 1614 and 1648.
If so, the manuscript could have spent generations hidden from colonial authorities.
The researchers interpret this concealment as potentially significant evidence of Indigenous resistance. Rather than simply preserving an old object, hiding the codex may have helped protect elements of a pre-Hispanic religious and calendrical worldview from the Spanish colonial religious system.
The manuscript may therefore have survived in secrecy for roughly two centuries before re-emerging.
From Concealment to European Collectors
The researchers believe the manuscript eventually came to the attention of the Italian historian and antiquarian Lorenzo Boturini, who is thought to have learned of its existence and acquired it around 1740.
This proposed history gives the codex a remarkable trajectory: created in the final decades before the Spanish conquest, potentially concealed during the colonial period, and eventually entering the collection of a European antiquarian more than a century after its presumed hiding.
Its survival provides an unusual connection between pre-Hispanic Indigenous traditions and the later history of collecting and studying Mesoamerican manuscripts.
Why the Codex's Age Was Disputed
Before the new scientific analysis, scholars had reached different conclusions about the manuscript's origins.
Some researchers considered the Aubin Tonalámatl to be a relatively rough copy of the Codex Borbonicus, another important Mesoamerican manuscript. Others suggested that it might instead have been produced during the colonial period as an imitation of an earlier Indigenous tradition.
Several artistic characteristics complicated the question.
Among them were the treatment of the so-called “flower” glyph and the layering of colours within the pictographic imagery. These features had contributed to uncertainty about whether the manuscript represented an authentic pre-Hispanic work or a later reproduction.
The new radiocarbon results provide an independent scientific line of evidence that substantially strengthens the case for a pre-Hispanic origin.
New Research Into Materials and Pigments
The dating study forms part of a much broader investigation involving 16 specialists from fields including physics, chemistry, biology, archaeology and history.
The resulting volume grew out of a symposium held in 2023 at Mexico's National Museum of Anthropology and the Institute of Historical Research.
Researchers have examined not only the age of the manuscript but also the materials used to produce it, the composition and possible origins of its pigments, and evidence of pentimenti — alterations, corrections or changes made during the creation of the images.
The studies also investigate the representation of deities and compare the Aubin Tonalámatl with the Codex Borbonicus.
These comparisons are particularly important because both manuscripts contain religious and divinatory imagery connected with Indigenous pictographic traditions.
An 18-Sheet Guide to the 260-Day Calendar
The Aubin Tonalámatl Codex consists of 18 sheets of amate paper, each measuring approximately 24 by 27 centimetres.
Together, the sheets form a continuous strip approximately 4.86 metres long. The manuscript was folded accordion-style into a screenfold format.
Unlike some related manuscripts, the amate paper used for the Aubin Tonalámatl does not have the coating known as chimaltizatl.
Its imagery records information associated with the tonalpohualli, the sacred 260-day calendrical cycle used in central Mexico.
The manuscript depicts deities and other symbolic elements connected with successive 13-day periods within the calendar. Its imagery therefore preserves information about systems of divination, religious belief and the interpretation of individual destinies.
A Rare Witness to Pre-Hispanic Indigenous Knowledge
The new scientific evidence significantly strengthens the interpretation of the Aubin Tonalámatl as a genuine pre-Hispanic manuscript.
Its importance extends beyond its age. The codex preserves a visual record of a religious and calendrical system that existed before Spanish conquest and continued to have significance even after colonial authorities attempted to suppress Indigenous religious traditions.
The possibility that the manuscript was deliberately hidden during the colonial period adds another dimension to its history. If the researchers' interpretation is correct, its survival may reflect deliberate efforts to protect Indigenous knowledge and religious traditions.
The proposed date of 1494 places the manuscript firmly within the final decades before the Spanish conquest, making it an especially valuable surviving witness to the intellectual and religious traditions of pre-Hispanic Mexico.
Conclusion
New carbon-14 analysis has provided the strongest scientific evidence yet for the pre-Hispanic origins of the Aubin Tonalámatl Codex.
With 1494 proposed as its most likely production date, the manuscript can now be placed within the late 15th-century Indigenous world that existed before Spanish rule.
The research also opens new questions about what happened afterward. Its possible concealment between 1614 and 1648 suggests that the codex may have survived colonial suppression through deliberate secrecy before eventually entering the collection of Lorenzo Boturini.
Combined with new research into its paper, pigments, imagery and corrections, the findings transform the manuscript from an object of uncertain origin into an increasingly well-understood record of pre-Hispanic Mexican religious and calendrical knowledge.
FAQ
How old is the Aubin Tonalámatl Codex?
Researchers propose 1494 as its most likely production date, placing it in the late 15th century and before the Spanish conquest.
What did carbon dating reveal about the codex?
Accelerator mass spectrometry carbon-14 dating indicates that the manuscript was produced no earlier than approximately 1450 and provides scientific support for a pre-Hispanic origin.
What is the Aubin Tonalámatl Codex?
It is an Indigenous Mexican divinatory manuscript containing pictographic representations associated with the tonalpohualli, the sacred 260-day calendar of central Mexico.
How many sheets does the codex contain?
The manuscript consists of 18 sheets of amate paper, forming a continuous strip approximately 4.86 metres long when unfolded.
What is the tonalpohualli?
The tonalpohualli was a 260-day sacred calendrical cycle used in central Mexico and associated with divination, religious practices and the interpretation of destinies.
Was the codex hidden during the colonial period?
Researchers propose that it may have been deliberately concealed between 1614 and 1648, potentially to protect it from Spanish authorities and the suppression of Indigenous religious manuscripts.
When did Lorenzo Boturini acquire the manuscript?
The Italian historian and antiquarian is believed to have learned of and acquired the codex around 1740.
Why was the codex's age previously uncertain?
Some scholars considered it a copy of the Codex Borbonicus, while others proposed that it was a colonial-era imitation. Its artistic characteristics also complicated attempts to determine its origin.
