In some dialects , however, special characteristics of the dialect created more or fewer tones. Thai, for example, now have five tones. In brief, these shifts resulted when the phonetic nature of the initial consonant of each syllable conditioned an allophonic pitch difference. Linguists frequently set a date as early as AD1000 for these sound changes. For the Thai spoken in Ayutthaya, however, the splits seem to have occured much later.
Several factors suggest a latter date for the splits in Thai.
Second, Khmer loanwords, which probably entered the language after the Thai conquest of Angkor in 1431, also predate the splits. In addition, seventeenth-century descriptions of the Thai alphabet demonstrate that the consonant changes involved with the tonal splits had already taken place by that date. These Indic loanwords comprise a large portion of the technical vocablaries for science, government, education, religion and literature. Sanskrit and, to a much lesser extent, Pali assume the same cultural importance for Thai as Latin does for English. Many of these loanwords exist in both short and a long forms.