The Abergavenney manuscript was a fragment of a journal kept by a Christian mountain-dwelling hermit during the early 8th century. It described several aspects of religious practices in Great Britain. Around 717 or 719, the hermit beheld vision of the Holy Grail (which according to the legend resided in Avalon).
In the 20th century, the manuscript was discovered in near Abergavenney, Wales during the research of Charles B. Hawken of Oxford University and referenced by the spring issue of The Celtic Scholar (1915), in the context of a conference on Celtic-British literature after the Saxon invasions.
Henry Jones considered contacting Marcus Brody to arrange a meeting with Hawken but when he arrived in Oxford in 1920, Hawken had passed on. Nevertheless, Jones was allowed to study the manuscript.