There are many variations
on the theme, but in outline, the history of the Celts is usually told as
follows.
(The outline presented here is obviously a vast oversimplification, but there is now also reason to think that the whole basis of the story may be unsatisfactory, as is explained in an alternative history of 'Celticism')
A coin of Dumnorix, prince of the Gallic Aedui at the time of Caesar. In his right hand he grasps a war-trumpet and a boar (battle standard? lunch?!) and in his left, it seems, a severed head...
(above, graves excavated in the 19th cent, Hallstatt, Austria. These are probably the people Greeks called Keltoi)
By around 8-600BC, in the lands just North of the Alps, peoples had appeared whom their literate Greek neighbours to the South came to call Keltoi.
These earliest known Celts formed principalities in the zone North of the Alps, and traded with the Greeks and Etruscans. Around 500BC these principalities were violently destroyed.
During the 400s, in a band of territory stretching across Europe from Eastern France through Germany, Austria and into Bohemia, new groups arose, characterised by, among other things, warrior graves and a new kind of art. Archaeologists call this the 'La Tène culture', the physical remains of groups who, around 400BC, suddenly erupted into Italy and began to settle the Po Valley.
(Left, a bronze
wine-flagon from Dürrnberg, Austria, 5th cent. BC, an early example
of 'Celtic' art (known to archaeologists as 'La Tène' style,
after the place it was first described). Below, the early Gaulish
migrations.)
These were the Ancient Celts par excellence, otherwise known as Gauls. No longer a distant scholarly curiosity, the Celts were suddenly the most fearsome 'barbarian' danger. Around 390BC, the Gallic Senones actually sacked Rome, but they were driven back and largely contained in the Po Valley which became Gallia Cisalpina, 'Gaul this side of the Alps'
(The Gaulish warriors of Northern Italy probably looked something like this in the 3rd cent. BC)
Migrating Celtic groups invaded the Balkans and, in 279BC, attacked Delphi, the greatest shrine in Greece. Beaten back with terrible losses, some nevertheless crossed into Anatolia (now Turkey) and established themselves as a kind of robber-kingdom around modern Ankara. Known by the Greek equivalent of the Roman name 'Gauls', these 'Galatae' gave their name to the land, Galatia, and so to the Galatians of the New Testament.
(The famous Classical statue, the Dying Gaul, actually depicts one of the Galatians of Anatolia)
It has also long been assumed that there were waves of Celts moving Westwards and North-West from the Central European homeland, to match these historically-attested Mediterranean migrations - even though there were no literate observers in these areas to record such invasions. Nonetheless, the Romans found people called Celtiberians in Spain, and there are traces of Celtic dialects in various parts of the peninsula. This has been explained as a result of early, unrecorded Celtic invasions.
(Detail of a stone
inscription from Botoritta, Spain, in Iberian letters, but the words are
apparently in a Celtic dialect)
(Small bronze head
depicting a mustachioed man, Welwyn, England. Late Iron Age)
Likewise, it has long been believed that there were Celtic invasions of the British Isles. Caesar recorded that Gauls, especially Belgae, had settled in Britain. Identical tribal names are found on the continent and in Britain (e.g.Atrebates, Parisi). Modern linguistics has shown that the indigenous tongues of the British and the Irish were closely related to those of the continental Gauls, and were all members of the Celtic family of languages.
Then as archaeology developed, the artefacts of Iron Age Britain and Ireland began to be identified, and in important ways showed links with the world of the Continental Celtic Gauls; all three groupings produced the same kind of characteristic 'Celtic' art, of swirling lines, suggesting vegetation, and perhaps stylised faces of people and animals. There seemed to be a common emphasis on weapons, strongholds, and warfare, and historical documents suggested institutions in common too, not least in religion; Druids, for example, are attested amongst all three groups.
The Ancient British and Irish, then, came to be seen as Celts like the Gauls and related continental peoples, from Spain to Turkey.
(Hadrian's Wall, a Roman military work built from sea to sea across Northen Britain in the AD 120s)
During the last three centuries BC, the expanding Roman empire gradually subjugated all of the Continental Celtic world, except for areas North of the Rhine and Danube, which were soon overrun by a new 'barbarian' grouping; the early Germans.
Many of the wholly or partly Celtic areas, such as the 'Three Gauls' (roughly modern France and the Rhineland) and Hispania (Spain and Portugal) became prosperous Roman provinces, but Celtic language and lifestyle did not survive the process of 'Romanization'. All these lands came to speak Latin dialects, ancestral to the 'Romance' languages of today (Spanish, French, Portugese, Catalan, etc.). Rome extinguished 'Celticity' on the European mainland.
(The cultural
exchange was not all one-way. This 'Celtic whirligig' is actually a sword-belt
fastener belonging to a Roman soldier, and was found at Dura-Europos on the
Euphrates, in Syria. 3rd century AD)
In Britain, Roman occupation of (roughly) the lands which would one day be
England and Wales led to a similar loss of Celtic language and culture in
the East of the island. Yet there was continuity of independence among the
'barbarians' of Caledonia (Northern Scotland), while Ireland was never invaded
by Rome at all. (The recently announced discovery of an alleged Roman 'military
base' at Drumanagh in Ireland was almost certainly a trading centre).
As the Empire began
to decay in the third and fourth century, the remnants of the free Celts
moved onto the offensive. In Caledonia, a new confederation, the Picts, appeared.
These threatened the Roman frontier, while Irish sea-raiders, known as 'Scotti',
raided the Western coasts, even as Germanic Angles and Saxons were raiding
the East.
In the fifth century
AD, Roman Britain collapsed, and the Anglo-Saxons invaded and settled the
East, eventually to establish Germanic-speaking England. They pressed the
native British groups, whom they called 'Welsh', ever westwards, into the
land which would become Wales, and Cornwall.
From the West, some Britons crossed to Armorica, the western extremity of Gaul, even as that land was being renamed France after its new Germanic overlords, the Franks. The British migrants were not so much refugees from Anglo-Saxon invasion as invaders themselves; conquest and migration was the name of the game at the time, and the Britons took this opportunity for some expansion of their own. Henceforth, the island of Britain was distinguished as 'Great Britain' to avoid confusion with this new 'little Britain' (Brittany).
The Irish, too, joined in the military free-for-all, slave-raiding their fellow Celts in Britain (their most famous captive being, of course, the young St. Patrick). They also settled in Britain, most importantly on the West coast of Scotland, which was to take its name from these settlers in Argyll; the land of these 'Scotti' became 'Scotia'. Eventually, wars with the Picts and other lesser kingdoms led to union into the historic kingdom of Scotland, in AD843.
Ireland itself became
a Christian land as a result of the work of St Patrick in the fifth century,
and became one of the greatest centres of piety and learning in Europe during
the seventh and eighth centuries AD, its clerics and artists having a profound
influence in Britain (not least among the English) and on the Continent.
The 18th century saw the beginnings of nationalism in Ireland and elsewhere, and the rediscovery of a common Celtic heritage. Linguistics, and the beginnings of archaeology, laid the foundation for more detailed understanding of the histories of these peoples, and contributed to growing national self-consciousness, exhibited in politics and in cultural forms, not least art and literature. Perhaps this process reached maturity with the establishment of an independent Irish state in 1921.
Today, not everyone accepts this established view of a Celtic history, and it is now possible to write an alternative history of 'Celticism'