Kumku is the eighteenth of the nineteen periods of the Haab and the last of its eighteen full twenty-day months, in the 365-day Maya solar calendar. Recorded here by its Yucatec name, Kumku, glossed as the granary and associated with the storehouse, the month is known from the colonial sources and the Classic inscriptions, and it is the Haab position named in the mythic Long Count creation date, 4 Ajaw 8 Kumku. Like each of the eighteen full months it counts twenty days, a Maya date naming the day by its place within the month together with its Tzolk'in day. After Kumku comes only the short five-day period that ends the year. These are the features of the Maya solar calendar, meshed with the 260-day sacred count in the fifty-two-year Calendar Round.
Kumku, the eighteenth and last of the full twenty-day months, closes the year's regular count before the five-day Wayeb, and its name appears in the best-known Long Count reference date of all, the creation date 4 Ajaw 8 Kumku, the day on which, per the standard GMT correlation, the current Long Count era is conventionally said to have begun, corresponding to 11 or 13 August 3114 BCE in the proleptic Gregorian calendar. Kumku's own etymology is not securely established among epigraphers, though its prominence in inscriptions is assured simply by its role marking the mythological starting point from which Classic Maya scribes counted every later Long Count date, making it, whatever its literal sense, one of the most frequently inscribed month names in the entire corpus of Maya monumental writing.