Historia Brittonum, an ancient history of Britain traditionally attributed to Nennius, a ninth-century Welsh monk, records that Arthur, the war leader of the Britons fought his first battle against the Anglo-Saxons at the mouth of the River Glein.

Cynvawr, in turn, is said by the ninth-century author Nennius, who compiled an early pseudo-historical account of King Arthur, to be identified with King Mark.

In the list of British towns given by the ancient historian Nennius, the name Caer Peris occurs, which some modern antiquarians suppose to have been transmuted, by a change of dialect, into Dumfries.

The practice seems to have very ancient antecedents, witness the names of the presumably 6th century poets Talhaearn Tad Awen, Blwchfardd and Culfardd, mentioned by the Welsh historian Nennius alongside Taliesin and Aneirin, the latter referred to as Aneurin Gwenithwawd.

However, Jerome, Isidore of Seville, and the Welsh historian Nennius stated another tradition that Tubal was ancestor to not only Iberians, but also the ' Italians ' Italic tribes and ' Spanish ' were also called Iberians.

Geoffrey of Monmouth, following the early Welsh historian Nennius, created a Christian / classical genealogy which placed Brutus of Troy, grandson of Aeneas and liberator of enslaved Trojans, as founder of Britain.

Some of these early poets ' names are known from the 9th century Historia Brittonum, traditionally ascribed to the historian Nennius.

The story is known from the Historia Brittonum, attributed to the Welsh historian Nennius, which was a compilation in Latin of various older materials ( some of which were historical and others mythic or legendary ) put together during the early 9th century, and surviving in 9th-century manuscripts – i. e., some 400 years after the supposed events.

Evidence suggests that this medieval literature was a compilation of several sources, some of which are named by Nennius while others are not.

The Prologue, in which Nennius introduces his purpose and means for writing the British History, first appears in a manuscript from the 12th century.

He also suggested that the name " Amros " in Breton genealogies is a contraction of " Ambrosius " and that Nennius refers to Aurelianus as supreme ruler of the Britons, which would translate as " Riothamus ".

According to 9th century monk and chronicler Nennius, north Wales was now defenseless and subject to increasing raids by mauraders from Mann and Ireland, a situation which led Cunedda, his sons and their entourage, to migrate in the mid-5th century from Manaw Gododdin ( Lothian, in modern Scotland ) to settle and defend north Wales against the raiders and bring the region within Romano-British control.

Nennius lists twelve battles fought by Arthur and gives him the title of " dux bellorum ", which can be translated as " war commander ", saying that Arthur fought " alongside the kings of the Britons ", rather than that Arthur was himself a king.

According to Nennius, Ambrosius was discovered when the British king Vortigern was trying to erect a tower.

He keeps this new figure separate from Aurelius Ambrosius, and to disguise his changing of Nennius, he simply states that Ambrosius was another name for Merlin.

The Historia Brittonum ( History of the Britons ), until recently attributed to a Nennius, a monk from Bangor, Gwynedd in Wales, was probably compiled during the early 9th century.

" Nennius " was the first to blacken the name of Vortigern.

Nennius was a Welsh monk of the 9th century.

Nennius was a student of Elvodugus, commonly identified with the bishop Elfodd who convinced British ecclesiastics to accept the Continental dating for Easter, and who died in 809 according to the Annales Cambriae.

Nennius was traditionally credited with having written the Historia Brittonum c. 830.

The work was translated into Irish by Giolla Coemgin in c. 1071 and is the earliest example of the original Historia Britonum, but includes the author ’ s name, Nennius.

Gwrangon was king of Ceint in the time of Vortigern according to Nennius.

Thomas Owen Clancy has argued that the Lebor Bretnach, the so-called " Irish Nennius ," was written in Scotland, and probably at the monastery in Abernethy, but this text survives only from manuscripts preserved in Ireland.

The foundation myth of Cornwall originates with the early Brythonic chronicler Nennius in the Historia Brittonum and made its way, via Geoffrey of Monmouth into Early Modern English cannon where it was absorbed by the Elizabethans as the tale of King Leir alongside that of Cymbeline and King Arthur, other mythical British kings.

Nennius recounts how Cunedda brought order to north Wales and after his death Gwynedd was divided among his sons ; Dynod was awarded Dunoding, another son Ceredig portioned Ceredigion, and so forth.

According to Nennius, Gwrangon was King of Kent in the time of Vortigern, until Vortigern took away the kingdom and gave it to Hengist ; but Nennius is regarded as an untrustworthy source, and “ Gwrangon seems to have been transported by the story-teller into Kent from Gwent ” and “ is turned into an imaginary King of Kent, secretly disposed of his realm in favour of Hengist, whose daughter Vortigern wished to marry ” ( Wade-Evans 1938 ).

There is no contemporary account of the events, but writing some 250 years later Nennius would say that Cadafael had left for home the night before the battle, in his ally's hour of greatest need, implying it was a deliberate decision ( i. e., by calling him the Battle-Decliner ).

The Trojan genealogy of Nennius was written in the Historia Brittonum of Nennius and was created to merge Greek mythology with Christian themes.

While Nennius ' Ambrosius eventually reveals himself to be the son of a Roman consul, Geoffrey's Merlin is begotten on a king's daughter by an incubus.

Nennius is commonly ascribed to be its author, since the preface is written in his name in certain manuscripts.

Nennius is believed to have lived in the area made up by present day Brecknockshire and Radnorshire counties in Powys, Wales.

The surviving manuscripts of the Historia Brittonum appear to be redacted from several lost versions: information about Nennius contained in the Prologue and in the Apology differs, the Prologue containing an expanded form of the Apology that is only found in editions copied during the 12th century, leading experts to believe that later versions of the document were altered.

Within the writing of Nennius is a sense of pseudo-nationalist pride attempting to legitimize the people of Britain and embellish the past through legend much as the Romans used the story of Romulus and Remus to legitimize the founding of Rome.

One such example of Nennius stressing legend is in his accounts of Arthur and his twelve battles.

This legend first appears in the Historia Britonum, a 9th-century historical compilation attributed to Nennius, but is best known from the account given by the 12th century chronicler Geoffrey of Monmouth in his Historia Regum Britanniae.

Caim is a Gaelic rendering of biblical ' Cain ', who appears in a variation of the fantastical pedigree of Dardanus of Troy that is spun out in Lebor Bretnach, the Middle Irish language recension of the compilation called Historia Brittonum, known in the 9th century version by Nennius.

Traditionally attributed to Nennius, its actual compiler is unknown ; it exists in several recensions.

The Historia Brittonum composed in the 9th century is traditionally ascribed to Nennius.

The earliest surviving reference to Partholón's settlement is in the Historia Brittonum, a 9th century British Latin compilation attributed to one Nennius.

Solsbury Hill is a possible location of the Battle of Mount Badon, fought between the Britons ( under the legendary King Arthur ) and the Saxons c. 496, mentioned by the chroniclers Gildas and Nennius.

Numerous fragments of Irish legendary history are scattered throughout the 7th and 8th centuries, but the earliest extant account is to be found in the Historia Brittonum or " History of the Britons ," written by the Welsh priest Nennius in 829-830.

The earliest written form of the name, ' Cetgueli ', is recorded by the monk, Nennius, writing in the 9th century.