How do ergative patterns work in Tibetan and other Tibeto-Burman languages?

In many Tibeto-Burman languages, including Tibetan, Newari, and Akha, ergativity is a key grammatical feature.1

In these languages, ergative patterns function by treating the subject of an intransitive verb the same way as the object of a transitive verb. This contrasts with accusative languages, which group the subjects of both transitive and intransitive verbs together. In the context of Tibeto-Burman grammar, agents in ergative constructions are typically marked similarly to instrumentals.21

Some languages within this family exhibit "split ergativity," such as Limbu and Sherpa. In these systems, ergative marking is not universal but is instead restricted to specific tenses or aspects, such as the past tense or completive aspect.1

It is important to note that the traditional notions of "subject" and "object" are often considered alien to the underlying structure of Tibeto-Burman languages, which are frequently topic-prominent and may lack formal subjects entirely in many clauses.1