From roughly the seventh century CE onward, Tibetan translation teams worked for centuries rendering Buddhist texts from Sanskrit into Tibetan, producing a body of material large enough that by the fourteenth century it needed active editorial sorting rather than simple accumulation. The scholar-monk Buton Rinchen Drub took on that task, dividing the translated corpus into two collections based on a single organizing question: was a given text held to record words the Buddha himself spoke, or was it a later composition commenting on or systematizing that teaching.
Texts answering the first description became the Kangyur, literally the translation of the word (bka', the Buddha's speech, and 'gyur, translation). Its contents span the Vinaya monastic codes, the large Prajnaparamita, Perfection of Wisdom, literature, other Mahayana sutras, and the tantras central to Vajrayana practice, arranged across roughly one hundred to one hundred and eight volumes depending on the edition, making it both a scriptural canon and, in its physical printed form, a devotional and ritual object in its own right within Tibetan Buddhist communities. Individual texts within the Kangyur range enormously in length, from short dharani incantations of only a few lines to sutras and tantras running to hundreds of pages, and the collection as a whole represents one of the largest sustained cross-linguistic translation projects in premodern Asian religious history.