260-day calendar used by the pre-Columbian Maya civilization
The tzolkʼin (Mayan pronunciation: [t͡sol ˈkʼin], formerly and commonly tzolkin) is the 260-day Mesoamerican calendar used by the Maya civilization of pre-Columbian Mesoamerica. The tzolkʼin, the basic cycle of the Maya calendar, is a preeminent component in the society and rituals of the ancient and the modern Maya. The tzolkʼin is still used by several Maya communities in the Guatemalan highlands. While its use has been spreading in this region, this practice is opposed by Evangelical Christian converts in some Maya communities.
https://en.wikipedia.org/wiki/Tzolk%CA%BCin