A small note does a large job
The end of a book can be a better place to begin an investigation than its cover. A colophon may identify when a copy was made, who sponsored it and why. Its scope is crucial: it describes an object or an act of production, which may be much later than the text it carries.
The International Dunhuang Programme explains that the colophon of the celebrated printed Diamond Sutra names Wang Jie as sponsor on behalf of his parents and gives a date equivalent to 11 May 868. It connects sponsorship and distribution with the Buddhist practice of acquiring merit. This is evidence about the production and stated dedication of that copy.
Sources: s1
Keep the qualifier attached
The British Library's Life in Ancient Dunhuang exhibition guide describes the scroll as the oldest complete printed book with a date. Each qualification matters. Complete is not the same claim as fragmentary; dated is not the same as earliest possible; a surviving example is not the same as the first object ever made.
A useful citation therefore identifies the object and repeats the exact scope of the comparison in paraphrase. Avoid expanding a catalogue superlative into 'the first book' or 'the invention of printing.' Neither conclusion follows from the survival and dating of this particular scroll.
What remains outside the evidence
The dedication does not reveal every reader, every stage of production or every belief held by the sponsor. A richer history needs other documents and objects. The strength of this case lies in a precise anchor: an identifiable surviving copy with a stated production date. Its gaps are questions to investigate, not permission to invent a biography.