The Royal Ceremonies of the Twelve Months (Thai: พระราชพิธีสิบสองเดือน, RTGS: phraratchaphithi sip song duean, also known by Pali/Sanskrit loanwords as phraratchaphithi thawathotsamat, พระราชพิธีทวาทศมาส) is a historical description of the annual royal ceremonies undertaken throughout the year by the monarchy of Siam (now Thailand).
They are described in the Palace Law of the Ayutthaya Kingdom (14th–18th centuries), and mentioned in the 15th-century Thawathotsamat epic poem.
[1] The ceremonies received renewed interest from the monarchy and aristocracy during the middle Rattanakosin period.
During the reign of King Mongkut (Rama IV, 1851–1868), Prince Mahamala [th] wrote an epic poem about the ceremonies, titled Khlong Phraratchaphithi Thawathotsamat (โคลงพระราชพิธีทวาทศมาส), which was first published in book form in 1920.
Mongkut's successor King Chulalongkorn (Rama V, r. 1868–1910) wrote and published, in prose, a treatise on the ceremonies titled Phraratchaphithi Sip Song Duean in 1888.