Old Tibetan

Old Tibetan refers to the earliest attested form of Tibetan language, reflected in documents from the adoption of writing by the Tibetan Empire in the mid-7th century to the early 9th century. In, during the reign of Tibetan King Sadnalegs, literary Tibetan underwent comprehensive standardization, resulting in Classical Tibetan.

Phonology

Old Tibetan is characterised by many features that are lost in Classical Tibetan, including my- rather than m- before the vowels -i- and -e-, the cluster sts- which simplifies to s- in Classical Tibetan, and a reverse form of the vowel letter for i. Aspiration was not phonemic and many words were written indiscriminately with consonants from the aspirated or unaspirated series. Most consonants could be palatalized, and the palatal series from the Tibetan script represents palatalized coronals. The sound conventionally transcribed with the letter འ was a voiced velar fricative, while the voiceless rhotic and lateral are written with digraphs ཧྲ and ལྷ. Unlike virtually all modern Tibetan languages, the Old Tibetan orthography did not contain silent letters, and the words were pronounced as written.
The following table is based on Hill's analysis of Old Tibetan:
In Old Tibetan, the glide occurred as a medial, but not as an initial.
The Written Tibetan letter ཝ w was originally a digraph representing two Old Tibetan consonants.
Vowel Phonemes of Old Tibetan

	Front	Central	Back
High	i ི	ɨ ྀ	u ུ
Mid	e ེ		o ོ
Low		a -

Syllable structure

In Old Tibetan, syllables can be quite complex with up to three consonants in the onset, two glides, and two coda consonants. This structure can be represented as, with all positions except C₃ and V optional. This allows for complicated syllables like བསྒྲིགས "arranged" and འདྲྭ 'drwa "web", for which the pronunciations and can be reconstructed.
A voicing contrast only exists in slot C₃ and spreads to C₁ and C₂ so སྒོ sgo "door" would be realized as while སྐུ "body" would be. Final consonants are always voiceless e.g. འཛིནད་ 'dzind and གཟུགས་ . The phoneme in C₁ was likely realized as e.g. བསྒྲེ and བརྩིས . The features of palatalization and labialization can be considered separate phonemes, realized as glides in G₁ and G₂ respectively. Only certain consonants are permitted in some syllable slots, as summarized below:

C₁	C₂	C₃	G₁	G₂	V	C₄	C₅
	^§ ^§	all consonants

^§ In C₂ position, and are in complementary distribution: appears before,,,,,,, and in C₃, while appears before,,,,, and in C₃. Additionally, is written before.

Palatalization

Palatalization was phonemically distinct from the onset cluster. This produces a contrast between གཡ and གྱ, demonstrated by the minimal pair གཡང་ g.yaṅ "sheep" and གྱང་ gyaṅ "also, and". The sounds written with the palatal letters ཅ c, ཇ j, ཉ ny, ཞ zh, and ཤ sh were palatalized counterparts of the phonemic sounds ཙ ts, ཛ dz, ན n, ཟ z, and ས s.

Morphology

Nominal

Case markers are affixed to entire noun phrases, not to individual words. Old Tibetan distinguishes the same ten cases as Classical Tibetan:

However, whereas the locative, allative, and terminative gradually fell together in Classical Tibetan, in Old Tibetan these three cases are clearly distinguished. Traditional Tibetan grammarians do not distinguish case markers in this manner, but rather distribute these case morphemes into the eight cases of Sanskrit.

Verbal

Old Tibetan transitive verbs were inflected for up to four stems, while intransitive verbs only had one or two stems. In the active voice, there was an imperfective stem and a perfective stem, corresponding to the Classical Tibetan present and past stems respectively. Transitive verbs also may have two passive voice stems, a dynamic stem and stative stem. These two stems in turn correspond to the Classical future and imperative stems.

Personal pronouns

Old Tibetan has three first person singular pronouns ང་ ṅa, བདག་, and ཁོ་བོ་, and three first-person plural pronouns ངེད་, བདག་ཅག་, and འོ་སྐོལ་. The second person pronouns include two singulars ཁྱོད་ and ཁྱོ་འདའ་ -'da' and a plural ཁྱེད་.