The Siamese writing (from Sian) comes from Khmere writing, They distinguish themselves from the first, for some particularities, some of them are the differences in texts drawing, the inexistence of auxiliary consonant's combination forms, perfect precision of accent intonation, and the possibility of exact transcription of all Sanskrit words, introduced in the language. The Siamese writing seams to be the consequence not of a gradual alteration came from a prolonged using but of a reflected and sudden transformation. The tradition attributes this reform to the Brahmans stabilised in this country and that intended to institute a new writing system, helped by the Siamesian linguists, better adopted to the necessities of the varied intonation of a monosyllabic language.