Although isolated glyphs (written signs) occur in Olmec art, the honour of inventing writing is generally thought to go to the inhabitants of the Oaxaca valley. Here a stela at San Jose Mogote dated before 500 BC, depicting a human sacrifice, bears both the name of the victim and some calendric information related to the calendar, showing that the Almanac year was already in use.
This consisted of two interlocking cycles, one of 13 numbered days interlocking with one of 20 days named after animals. It has been suggested that the choice of jungle animals for these may imply that the system began in the tropical Gulf coast region rather than in the highlands.
At Monte Alban before 400 BC the famous 'Danzantes' reliefs are also associated with dates, in both the Almanac year and the 365 day solar year. These two systems of dating ran together to produce the Calendar Round, a calendar cycle that repeated itself every 52 years.
However, it was only the Maya who added to this the Long Count, a historical system counting intervals of time elapsed since an initial date in 3114 BC.
