The Historia Brittonum (History of the Britons), which evidently originated in early-9th century Wales, has survived, in several versions (recensions), in more than thirty medieval manuscripts. The principal, i.e. fullest, text is to be found in Harleian MS 3859 (in the British Library, London) – which also contains the A-text of the Annales Cambriae and the earliest Welsh collection of royal genealogies. The Harleian manuscript dates from c.1100, but internal evidence suggests that the Historia text was originally compiled c.829.[*] Traditionally, on the strength of a prologue that features in just a handful of manuscripts (Harleian MS 3859 is not one of them), the work has been attributed to Nennius[*]:
I, Nennius, pupil [discipulus] of Elvodugus, have undertaken to write down some extracts that the stupidity of the British nation cast out; for the scholars of the island of Britain had no skill, and set down no record in books. I have therefore made a heap of all that I have found, both from the annals of the Romans and from the chronicles of the Holy Fathers – that is Hieronymus, Eusebius, Isidore and Prosper – and from the annals of the Scots [i.e. Irish] and the Saxons, and out of the tradition of our elders. Many learned scholars and copyists have tried to write, but somehow they have left the subject more obscure, whether through repeated pestilence, or frequent calamities of war. I ask every reader who reads this book to pardon me for daring to write so much here after so many, like a chattering bird or an incompetent judge. I yield to whoever may be better acquainted with this skill than I am.[*]
None of the surviving manuscripts of this, so-called, ‘Nennian recension’ is earlier than the 12th century,[*] though a text of the recension was translated from Latin into Middle Irish during the later-11th century.[*] The attribution to Nennius is now generally regarded as an 11th century invention.[*] Nevertheless, “a heap” might be considered a reasonable description of the miscellaneous assortment of material, riddled with errors and inconsistencies, presented by the Historia Brittonum.
The contents of Harleian MS 3859 can be categorized as follows –
§§1–6: The Six Ages of the World. §§7–18: British, Irish and Pictish origins. §§19–30: Roman Britain. §§31–49: The Adventus Saxonum story. §§50–55: Life of St Patrick. §56: Arthur’s battles. §§57–61: Genealogies of Anglo-Saxon kings. §§62–65: Northumbria. §66: Chronological computations. §66a: Cities of Britain. §§67–76: The Wonders of Britain, Anglesey and Ireland.[*]
Though it is clearly intended to provide a survey of the past history of the British it is an ill-synthesized and ill-digested work; the compiler gathered together and transcribed more or less relevant documents of very different types. Its contents, therefore, are very varied …Wendy Davies Wales in the Early Middle Ages (1982) Appendix
Indeed, a good deal of the Historia is clearly fantasy.
Much of the work consists of passages which, save that they lack the introduction ‘once upon a time’, have all the historical reliability of fairy-stories.A.S. Esmonde Cleary The Ending of Roman Britain (1989) Chapter 5
On the other hand, it must, so the theory goes, also contain historical nuggets.
Considerations of plausibility, the Historia’s relation to earlier sources, its chronology and compatibility with the archaeological evidence – all these combine to suggest that the Historia does contain genuine early information, albeit in a very adulterated form.Michael E. Jones The End of Roman Britain (1996) Appendix 4
The problem is that an objective method of sorting the wheat from the chaff has never been forthcoming; you pays your money and you takes your choice of what commends itself to you at the time.A.S. Esmonde Cleary The Ending of Roman Britain Chapter 5
It is impossible, therefore, to generalize about the value of the Historia Brittonum. On the one hand it provides first-hand evidence of the attitude to history writing of a Welshman of the early ninth century. On the other it presents us with edited documents of varying dates and provenances whose origins are not yet sufficiently understood; at the least, however, the latter indicates some of the materials that were available to the historian in the early ninth century.Wendy Davies Wales in the Early Middle Ages Appendix