"tzolk'in is the name bestowed by mayanist scholars upon the version of the 260-day mesoamerican calendar which was used by the maya civilization of pre-columbian mesoamerica. the tzolk'in, the most fundamental and widely-attested of all the maya calendars, was a pre-eminent component in the society and rituals of the ancient maya. the word, meaning "count of days", was coined based on yukatek maya. the maya used several cycles of days, of which the two most important were the tzolk'in, or sacred round of 260 days and the approximate solar year of 365 days or haab. the sacred round combined the repeating cycle of numbers 1-13 with 20 day names... so that any particular combination would recur in 13 x 20 or 260 days; the day name and the number changed together: 1 imix, 2 ik, 3 akbal... as we might say monday 1, tuesday 2, wednesday 3, and so on."