The Codex Aubin chronicles Aztec history starting with their migration from the mythic Aztlan, through the founding of the seat of their empire, Tenochtitlan, and through the Spanish conquest up to 1607. It opens,
"Written here is the year count of the Mexica. It's made of only four parts that go as follows: the year 13 ācatl ends the part beginning with 1 ācatl, 13 Tecpatl ends the one beginning 1 Tecpatl, 13 Calli the one beginning with 1 calli, and 13 Tōchtli the one beginning with 1 Tōchtli. When the four parts have come to an end, after 52 years, our years are tied on the year 2 ācatl.
This was written in Mexico on the 27th day of the month of September of 1576."