The 12th-century cleric Geoffrey of Monmouth provides us with our earliest information on Merlin. Geoffrey of Monmouth wrote about the early history of Britain in Historia Regum Britanniae (the "History of the Kings of Britain") and Vita Merlini ("Merlin's Life"), which was adapted from Celtic mythology. Being mythology-based, Merlin's Life is not enough to say Merlin ever lived. To determine when Merlin may have lived, one way would be to date King Arthur, the legendary king with whom Merlin is associated.
Geoffrey Ashe, a historian, and co-founder and secretary of the Camelot Research Committee wrote about Geoffrey of Monmouth and the Arthurian legend. Ashe says Geoffrey of Monmouth connects Arthur with the tail end of the Roman Empire, in the late 5th century A.D.:
"Arthur went over to Gaul, the country now called France, which was still in the grip of the Western Roman Empire, if rather shakily."
"This is one of the clues, of course, to when Geoffrey of Monmouth thinks all this is happening, because the Western Roman Empire ended in 476, so, presumably, he's somewhere in the 5th Century. Arthur conquered the Romans, or defeated them at least, and took over a goodly part of Gaul… "
- from (www.britannia.com/history/arthur2.html) Basic Arthur, by Geoffrey Ashe
The 1st Use of the Name Artorius (Arthur)
The name of King Arthur in Latin is Artorius. The following is a further attempt to date and identify King Arthur that places Arthur earlier in time than the end of the Roman Empire, and suggests the name Arthur may have been used as an honorary title rather than a personal name.
"184 - Lucius Artorius Castus, commander of a detachment of Sarmatian conscripts stationed in Britain, led his troops to Gaul to quell a rebellion. This is the first appearance of the name, Artorius, in history and some believe that this Roman military man is the original, or basis, for the Arthurian legend. The theory says that Castus' exploits in Gaul, at the head of a contingent of mounted troops, are the basis for later, similar traditions about King Arthur, and, further, that the name Artorius became a title, or honorific, which was ascribed to a famous warrior in the fifth century."
Does King Arthur Belong to the Middle Ages?
Certainly, the legend of King Arthur's court started in the Middle Ages but the putative figures on which the legends are based, appear to come from before the Fall of Rome.
In the shadows between Classical Antiquity and the Dark Ages lived prophets and warlords, druids and Christians, Roman Christians and the outlawed Pelagians, in an area sometimes referred to as Sub-Roman Britain, a pejorative label suggesting that the native British elements were less advanced than their Roman counterparts.
It was a time of civil war and plague -- which helps explain the lack of contemporary information. Geoffrey Ashe says:
"In dark age Britain we have to recognize various adverse factor, such as the loss and destruction of manuscripts by invading armies; the character of the early material, oral rather than written; the decline of learning and even literacy among the Welsh monks who might have kept reliable records. The whole period is plunged in obscurity from the same causes. People who were certainly real and important are no better attested."
Since we don't have the necessary fifth and sixth-century records, it's impossible to say absolutely that Merlin did or did not exist.
Legendary Roots - Possible Merlins
Transformation of Celtic Mythology in Arthurian Legend
- There may have been a real Merlin, such as the one Nikolai Tolstoy describes in Quest for Merlin: "… Merlin was indeed an historical figure, living in what are now the lowlands of Scotland at the end of the sixth century A.D… an authentic prophet, most likely a druid surviving in a pagan enclave of the north."
- The Merlin prototype may have been a Celtic druid named Lailoken who gained second sight after he went mad and escaped society to live in the forest.
- A poem from A.D. 600 describes a Welsh prophet named Myrddin.
The 9th-century monk Nennius, described as "inventive" in his history writing, wrote about Merlin, a fatherless Ambrosius, and prophecies. Despite Nennius' lack of reliability, he is a source for us today because Nennius used fifth-century sources that are no longer extant.
Math, the Son of Mathonwy
In Math, the Son of Mathonwy, from the classic collection of Welsh tales known as the Mabinogion, Gwydion, a bard, and magician, performs love spells and uses cunning to protect and help an infant boy. While some see this Gwydion trickster as Arthur, others see in him Merlin.
Passages From Nennius' History
Sections on Vortigern include the following prophecy referred to in Part I of the Merlin television mini-series:
"You must find a child born without a father, put him to death, and sprinkle with his blood the ground on which the citadel is to be built, or you will never accomplish your purpose."
The child was Ambrose.
ORB Sub-Roman Britain: An Introduction
Following barbarian raids, troop withdrawals from Britain ordered by Magnus Maximus in A.D. 383, Stilicho in 402, and Constantine III in 407, the Roman administration elected three tyrants: Marcus, Gratian, and Constantine. However, we have little information from the actual time period--three dates and the writing of Gildas and St. Patrick, who rarely writes about Britain.
In A.D. 540, Gildas wrote De Excidio Britanniae ("The Ruin of Britain") which includes a historical explanation. This site's translated passages mention Vortigern and Ambrosius Aurelianus.
Geoffrey of Monmouth
In 1138, combining Nennius' history and Welsh tradition about a bard named Myrddin, Geoffrey of Monmouth completed his Historia Regum Britanniae, which traces the British kings to the great-grandson of Aeneas, Trojan hero and legendary founder of Rome.
In about A.D. 1150, Geoffrey also wrote a Vita Merlini.
Apparently worried that the Anglo-Norman audience would take offense at the similarity between the name Merdinus and merde, Geoffrey changed the prophet's name. Geoffrey's Merlin helps Uther Pendragon and moves the stones to Stonehenge from Ireland. Geoffrey also wrote a Prophecies of Merlin which he later incorporated into his History.