This paper describes the creation of a syntactically annotated Tibetan corpus. This corpus forms a part of the TUSNELDA collection of corpora and databases for linguistic research. It will ultimately comprise spoken and written Tibetan texts originating from different regions and historical epochs. These texts are annotated with several kinds of linguistic information, in particular POS tags, phrases, argument structures of verbs, clauses and sentences, as well as several kinds of discourse units and textual segments. The annotation is done in XML. The primary research interest which guides the development of the corpus is the investigation of cross-clausal references, especially the relation between empty arguments (i.e. arguments not overtly realised in a clause) and their antecedents in previous clauses. For this purpose, such references are explicitly encoded so that they can be qualitatively and quantitatively evaluated with the help of standard XML techniques such as XPath search and XSLT transformations. Apart from this primary research interest, we expect that our corpus will be useful for other projects concerning Tibetan and related languages. Like other data in TUSNELDA, it will be made accessible via a WWW query interface.