The Celts were an ancient European people that occupied the central areas of Europe from Asia Minor to the Iberian peninsula to Britain.  To the south they were bordered by the Romans and Greeks, to the north by the Teutons (Germans).  The Celts were an advanced people.  In 396 BC, the Gauls, a Celtic people, sacked Rome and took all its treasure.  Their leader, Brennus, issued the famous phrase, "Vae victis!," meaning, "Woe to the conquered!"

The Celts were among the first peoples to develop abstract art.  They made intricate gold artifacts and decorated them with abstract shapes.  The "Celtic knot" remains a prominent feature of Celtic art.  The Celtic knot has no beginning and no end, but turns in upon itself forever.  Unlike other peoples of that period, who concentrated on figures of people and animals, the Celts developed designs that focused on abstract shapes and symbols.

Most of the Celts were eventually conquered by the Romans, but maintained a distinct culture throughout the period.  In Gaul , Celtiberia, and Galicia, assimilation was fairly complete by the 5th century.  In Britain, Celtic culture burst into dominance as soon as Roman rule was lifted.  Indeed, in Ireland the Celts had remained completely free.  Until the English fully conquered the island in the 17th century, Ireland had lived under at least 3000 years of Celtic self-rule.

The Anglo-Saxon hordes eventually overwhelmed the Celts of Britain and drove them from most of what is now Britain.  By the 9th century, the boundaries of what are now commonly known as the Celtic Nations had developed.  Ireland was of course still Celtic.  In Scotland, the Picts and the Scots merged to form the Celtic kingdom of Dalriada.  In Wales the British Celts held out against the Saxons.  In Cornwall, some British Celts held onto a thin strip of land, only to be conquered late in the 9th century.  In Brittany, Celts lived independently for a time, consisting mainly of refugees from Wales and Cornwall.

Eventually all the Celtic countries were conquered: Brittany by France, Wales by England, and Ireland by Great Britain.  Scotland merged with Great Britain to form the United Kingdom in 1707: it was technically equal to England, but it may as well have been a subject state.  As in all the other Celtic nations, the English instituted policies oppressing and persecuting the Celts and their culture.  Today, one Celtic country, Ireland, has gained at least partial independence from its captors.  Promising developments are also afoot in Scotland and Wales.  It should also be noted that the Isle of Man, an essentially Celtic nation which once had a unique Celtic language called Manx, is semi-independent.