Academic journal article Journal of Southeast Asian Studies

Southeast Asian Intercalation: Variations and Complexities

Academic journal article Journal of Southeast Asian Studies

Southeast Asian Intercalation: Variations and Complexities

Article excerpt

One of the constant problems for historians of Southeast Asia is to assimilate its system of adding extra days and extra years to the lunar calendar to make it keep pace with the solar calendar. It is well known that the addition of an extra month should take place 7 times in every 19 years (adhikames), and that the addition of an extra day should occur 11 times in every 57 years (adhikawan). It is also known that the extra month is called second Ashadha and that in Thailand and Cambodia the extra day is given to the previous month, Jyestha.(1)

The Burmese, however, observe a rule that differs from that of the Thai, Lao, and Cambodians. These latter say that if a year has an extra month, it cannot also have an extra day: the Burmese, on the contrary, say that the extra day has to be placed only in years that also have an extra month. In a span of 57 years, both groups employ 21 extra months and 11 extra days -- 641 days, but their mode of implementation necessarily creates a difference that can be resolved only twice a century -- if then. Nor can one suppose that the Thai, Lao, and Cambodians are all in step with each other. The best that can be said is that after a 57-year cycle the conflicting systems might all fall back into line: having the same long-term objective, they will not get progressively more and more out of kilter with each other.

What is the historical evidence for this difference in practice? The Luang Prasert Chronicle from Ayuthia provides a useful (because rare) example, when it says that Burma declared CS (the era in common use: chulasakarat or sakamat in Thailand, Laos, and Cambodia; thetkaint in Burma) 732 (1370 AD) would not have an extra month, would not be adhikamasa -- "but it was in Ayuthia". One's speculation is that the Burmese message had political overtones, that they were trying to dictate to (rather than simply to inform) the Thai on this matter. But whatever the political implications, the Chronicle indicates that the two calendars went out of phase in that year.

One can best acquire some perspective on these differences of reckoning by examining calendrical sequences that extend over a longish period: Faraut for Cambodia, Thong Chua for Thailand, and Irwin for Burma are useful here.(2)

The first (encouraging) thing to emerge is that the years chosen to contain an intercalary month could be the same across a wide area. If one begins a sequence of 19 years at CS 1217 = BS 2398 = AD 1855, the years attracting an extra month in Thailand, Cambodia, Burma, and Sipsongpanna were:(3)

year   1       4      7      9     12      15     18

CS     1217   1220   1223   1225   1228   1231   1234.

One must be wary, however, of reading too much conformity into the overall arrangement. As already hinted, we have Irwin's assurance (and a lengthy table demonstrating his point) that "the practice of placing the intercalary . . . day always at the end of Nayon |= Jyestha~, and only in a year which has an intercalary month, is still |ca. 1909~ adhered to".(4) Immediately, then, there is a systematic difference in reckoning, since the Burmese will count 385 days in years 1, 4, 7 . . ., and the rest will count only 384 days.

One might also expect to find that some parts of Thailand could not resist influence from the Burmese, given the importance of the calendar in organizing the social and religious life of the community and the constant Burmese incursions into the area. But though the Burmese style of reckoning lunar months makes Ashadha the 9th month, and though a number of Thai records (extending as far south as Lampang and Lamphun) use that mode, the calendrical evidence suggests that the Thai did not also insert an extra day into an adhikamasa year. Instead, they obey the Thai/Cambodian rule that requires Jyestha to receive the extra day in a year that is not also adhikamasa. The 100-year Calendar, a northern MS Calendar, and the Sipsongpanna data, for instance, all use Burmese month numeration, but all use Thai adhikavara reckoning. …

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