Origins of the Thai script…
We can trace the Thai script back in time and space (mostly going West) to the Phoenicians, whose alphabet is the mother of all European and Indic systems of writing, including Greek, Hebrew and Arabic! These people were great traders and had links to lands beyond the river Indus. So East went their written words…
But back to the Thai script (we are NOT referring to the language here!). Modern Thai letters are an evolution from the old form used in Sukhothai and they were devised under the King Ramkhanhaeng transforming the Khmer characters in use at that time, when the Thais broke free from the Khmer kingdom. Some were just inversed, others had to be doubled to accommodate the different tones (see the difficulty of adapting a non tonal alphabet previously only used by polysyllabic tongues for a tonal, essentially monosyllabic language!). Strict concern for the faithful rendition of Sanskrit and Pali vocabulary was applied (not the case with Lao). That is why we find those “useless” letters at the tail of Sanskrit and Pali words.
Old Khmer was itself derived from the Pallawa of South India of about the 6th century.That was a local evolution from the Gupta script of North India (4 AC) which itself came from the Brahmi used by Emperor Ashoka (circa 2 BC).That Brahmi alphabet had been sequenced under the very logical and clever Sanskrit system (a language and NOT a script!) By classifying each letter according to the area of the human organs of speech where they are formed, into five series of five letters (plus some): Guttural, retroflex, palatal, dental and labial (thus moving from the throat to the lips). Brahmi itself came from the writing of the land now known as Lebanon: Phoenician, circa 1000 BC.
Now going in the sense of time and going East, we see that its evolution in diverse regions gave birth to forms as diverse as Devanagari of North India, Ranjana, Tibetan, Bengali, Panjabi, Gujerati, Orissi, Telugu/Kannara, Tamil, Malayalam, Sinhala, old Javanese and Balinese, Mon and Burmese, Khmer, Lao, Tham and related Shan and Dai, old Cham.
The amazing fact about all those scripts, apart from the fact that they are traceable in an almost unbroken line across time and space, is that they still all follow the original Sanskrit ordering (except for Old Javanese and Balinese because a very clever poem was created using the phonemes for easy and fun memorizing). So,just allowing for the small changes to the specific phonemic necessities of each language, we always find these five series of five sounds, plus some: YA RA LA WA HA SA SHA ShA A, mentioned earlier (starting with Guttural: KA, KHA, GA, GHA, NGA of Sanskrit, becoming, for instance: KA, KHA, KHA, KHA, NGA in Thai).
Are we amazed?… Well, I, for one, am!