Aztec navigation · Mexica and Nahua evidence
Two counts, kept in their own language
The tonalpohualli advances thirteen numbers against twenty Nahuatl day signs. The annual count moves through eighteen veintenas and five nemontemi. Their arithmetic resembles other Mesoamerican calendars; their names and historical problems are not interchangeable.
20 signs × 13 numbers · 18 veintenas + 5 nemontemi
The twenty day signs
The order below follows Book 4, folio 82r of the Florentine Codex as catalogued by the Getty Research Institute. Glosses identify the pictured signs; they are not personality keywords.
| position | sign | Nahuatl name | English gloss |
|---|---|---|---|
| 1 | Cipactli | Crocodile | |
| 2 | Ehecatl | Wind | |
| 3 | Calli | House | |
| 4 | Cuetzpalin | Lizard | |
| 5 | Coatl | Serpent | |
| 6 | Miquiztli | Death | |
| 7 | Mazatl | Deer | |
| 8 | Tochtli | Rabbit | |
| 9 | Atl | Water | |
| 10 | Itzcuintli | Dog | |
| 11 | Ozomahtli | Monkey | |
| 12 | Malinalli | Grass | |
| 13 | Acatl | Reed | |
| 14 | Ocelotl | Jaguar | |
| 15 | Cuauhtli | Eagle | |
| 16 | Cozcacuauhtli | Vulture | |
| 17 | Ollin | Movement | |
| 18 | Tecpatl | Flint | |
| 19 | Quiyahuitl | Rain | |
| 20 | Xochitl | Flower |
Images: Codex Magliabechiano, mid-16th century, Biblioteca Nazionale Centrale di Firenze. Public-domain Loubat facsimile crops via Wikimedia Commons; day numerals were excluded from each crop.
The nominal conjunction
260 days
Tonalpohualli
Thirteen numbers and twenty signs return to the same pairing after 260 days.
365 days
Annual structure
Eighteen groups of twenty plus five nemontemi make the nominal 365-day count.
18,980 days
Binding of Years
Seventy-three ritual counts equal fifty-two nominal 365-day years. Mexica New Fire evidence belongs to this history.
No Gregorian converter yet
Colonial sources and modern reconstructions disagree about the year’s first veintena, European alignment and seasonal adjustment. Bodhastra tests the relative cycle arithmetic but does not disguise one reconstruction as your uncontested birth date.