Abstract:
The study of language change aimed to study Morphology and language changes in the Phayao inscription. The 55 Phayao inscriptions selected for the study of language changes in each Buddhist century, classified into 3 groups according to the period of the inscription. The criteria used for selecting the inscription with the number of words in each inscription were; 5 inscriptions with 1-10 lines, 15 inscriptions with 11-20 lines, 16 inscriptions with 21-30 lines, 6 inscriptions with the 31-40 lines, 13 inscriptions with more than 41 lines. Findings showed both language changes and unchanged form in three aspects; (i) in terms of form, there is a selection of with the use the initial consonant, spelling consonants, tonal vowels, which are different from the present in terms of the form of loss, reduction of consonants, addition of consonants, vowels and tonal forms, (ii) for the word use, different words or using different words to the present are used, they are more common in pronouns, classifiers, name titles,(iii) in terms of compilation of word, it is different from the present, which is found in the compilation of numbers and noun classifiers. In language features with unchanged form, word formation system for doublet word, compound word, complex word, and the combination of words. The system of change of the word kind of noun, pronoun, noun classifier, quantifies, address terms, is similar to the present system.