Tibetan Tha ཐ

Tha is the tenth of the thirty consonants and the aspirated partner of ta: a dental stop released with an audible breath. The name is a trap for an English reader, because the letter is not the th of thin and Tibetan has no interdental fricative of any kind. The h in the transliteration marks aspiration on the letter before it, as it does in kha, cha, pha and tsha, and it never stands for a separate sound.

In modern Lhasa speech ta and tha have merged as an aspirated dental with high tone, following the pattern set by the velar and palatal lines above. Tha is a root letter with no orthographic office, and it takes the ra and wa subscripts.

Its place in the recitation is the third repetition of a single pattern: a place of articulation, four letters, unaspirated then aspirated then voiced then nasal. By the time a reciter reaches tha the pattern is established well enough to be predicted, and the value of the arrangement is that it turns thirty separate shapes into a small number of positions. A letter is not learnt on its own; it is learnt as the second of the dentals, and its sound, its tone behaviour and its relation to the letter before it all follow from that.

The transliteration difficulty is worth a further word, because it recurs across the alphabet. Any roman rendering of Tibetan that puts an h after a consonant is marking aspiration on that consonant, and a reader who takes tha, pha, cha and tsha as digraphs of the English kind will mispronounce a third of the letters.

Tibetan writing has a beginning that can be dated to a century and a story that cannot be taken at face value.

The traditional account, transmitted in Tibetan histories, credits the minister Thonmi Sambhota, sent to India by the emperor Songtsen Gampo in the seventh century, with bringing back a script and composing the first grammatical treatises of the language. The account is old, it is universally known within the tradition, and the two treatises attributed to him are still the basis of how Tibetan grammar is taught.

Modern scholarship does not reject the seventh century. The earliest Tibetan inscriptions and documents are consistent with a script created or adapted in that period under imperial patronage, for the practical purposes of a state that had just acquired an empire and needed to write. What scholars treat with caution is the rest: the figure of Thonmi himself is attested only in much later sources, the surviving grammatical treatises show signs of later composition, and which Indic script served as the model is disputed rather than settled.

The atlas records both parts honestly. That the script descends from the Brahmi family is not in doubt and is stated as such. Which script of that family stood immediately behind it, and how much of the traditional account is history, are open, and the entries say so rather than choosing.