While the use of noble rank and title words are found in the documents of many early
Tai city states including
Sukhothai, the earliest extensive descriptions are from the administrative reforms introduced in 1448 by King
Borommatrailokanat of Ayutthaya, which by then had become the dominant polity in the region. The reforms established official titles for high-ranking ministers of the
chatusadom system, and the rank of
phra was added to the previously used
khun and
nai, in order to accommodate the expanding machinery of government. (The ranks
luang and
okya were further introduced during the mid- and late-16th century, respectively.) The
sakdina system, which assigned a numeral rank representing the amount of land one was entitled to own, was also officially described. Nobles were not directly remunerated for their service, but enjoyed earnings and benefits derived from their office and the work of commoners (
phrai) under their command. Unlike in European aristocracies, Thai noble titles were not inherited, but individually granted by the king or his ministers based on personal merit. Noble families could, however, present their sons to the royal household, placing them at an advantage to succeeding in those positions. This practice became especially influential from the 17th century, when war subsided and commerce flourished, leading personal patronage to displace martial ability as the determining factor for promotions. Several noble families gained much power and influence during the late Ayutthaya period, and even more so during early Rattanakosin; some, such as the
Bunnags, effectively became as powerful as the monarchy. King
Chulalongkorn (Rama V, r. 1868–1910) introduced reforms that ended the system that allowed nobles to command manpower, and transformed titled nobles into paid officials under a modern civil service system. His successor
Vajiravudh (Rama VI, r. 1910–1925) introduced a military-style promotion-based rank system, superseding the traditional titles, though they could still be granted at the king's discretion. Following the abolition of absolute monarchy in 1932, royal decrees issued during the government of
Plaek Phibunsongkhram in 1942 abolished the use of noble titles and the rank system. While the decree abolishing titles was repealed by the
Khuang Aphaiwong government two years later, allowing previously held titles to be reinstated, the granting of noble titles never resumed after 1932. ==Noble titles==