The Balinese ritual year is ruled by a complex calendar system which combines the Saka calendar with the Wuku calendar. Since the calendar is ruled by the lunar cycle, the precise Gregorian dates of the ceremonies differ from year to year. The years are numbered 70 years behind the Gregorian year. In the Balinese year, the year 2000 is year 1930.
The Saka calendar, which is also the official Indian calendar, was imported from India during the Majapahit empire. It is divided into lunar months and fitted into the solar calendar by the addition of an extra month, every thirtieth month. The full moon and the dark moon are the most important ritual moments of this calendar. The first day of the Saka year, however, usually in March is the day of Silence and of profound importance throughout Bali.
The Wuku – or pawukon - calendar is the original calendar used by the Bali Aga people – Bali's aboriginals. The wuku year consists of a cycle of 210 days divided into thirty wuku weeks, each of which corresponds to a specific activity. There is a week of weapons and one of animals, for example. There are then other types of weeks varying from one to ten days, each having a name and number, being auspicious or inauspicious. The most important days in this system are Galungan and Kuningan, when all the ancestors come down to visit.