Short answers, pulled from the story.
Classical Tibetan emerged as a distinct form during the reign of King Sadnalegs in the 9th century. This period marked a crucial standardization effort that separated it from earlier Archaic and Old Tibetan forms.
Scholars recognize four main chronological stages: Archaic, Old, Classical, Medieval, and Modern. The language used to translate Sanskrit texts from the Mahāyāna Buddhist canon began appearing in the seventh century.
Hodge's description reveals a phonology very similar to Old Tibetan with silent prefixes except for db- when preceding a, e, or o. Suffixes -g and -b are devoiced to /k/ and /p/, while suffixes -d and -s remain silent in most instances.
Case markers affix to entire noun phrases because traditional Tibetan grammarians distribute these case morphemes into the eight cases of Sanskrit instead of distinguishing them individually. Nominalizing suffixes or are required by the noun or adjective that is to be singled out.
Tibetan verbs fall into one of two categories based on agent involvement where the first category expresses implicitly or explicitly the involvement of an agent marked by the instrumental particle. The second category expresses an action that does not involve an agent.