The Celts
The Celts were a group of peoples that occupied lands stretching
from the British Isles to Gallatia. The Celts had many dealings
with other cultures that bordered the lands occupied by these
peoples, and even though there is no written record of the Celts
stemming from their own documents, we can piece together a fair
picture of them from archeological evidence as well as historical
accounts from other cultures.

The first historical recorded encounter of a people displaying
the cultural traits associated with the Celts comes from northern
Italy around 400 BC, when a previously unkown group of barbarians
came down from the Alps and displaced the Etruscans from the
fertile Po valley, a displacment that helped to push the Etruscans
from history's limelight. The next encounter with the Celts came
with the still young Roman Empire, directly to the south of the Po.
The Romans in fact had sent three envoys to the beseiged Etruscans
to study this new force. We know from Livy's The Early History of
Rome that this first encounter with Rome was quite civilized:
The Celts told the Roman envoys that this was indeed the first
time they had heard of them, but they assumed the Romans must be a
courageous people because it was to them that the [Etruscans] had
turned to in their hour of need. And since the Romans had tried to
help with an embassy and not with arms, they themselves would not
reject the offer of peace, provided the [Etruscans] ceded part of
their seperfluous agricultural land; that was what they, the Celts,
wanted.... If it were not given, they would launch an attack before
the Romans' eyes, so that the Romans could report back how superior
the Gauls were in battle to all others....The Romans then asked
whether it was right to demand land from its owners on pain of war,
indeed what were the Celts doing in Etruria in the first place? The
latter defiantly retorted that their right lay in their arms:
To the brave belong all things.
The Roman envoys then preceded to break their good faith and
helped the Etruscans in their fight; in fact, one of the envoys,
Quintas Fabius killed one of the Celtic tribal leaders. The Celts
then sent their own envoys to Rome in protest and demand the Romans
hand over all members of the Fabian family, to which all three of
the original Roman envoys belonged, be given over to the Celts, a
move completely in line with current Roman protocol. This of course
presented problems for the Roman senate, since the Fabian family
was quite powerful in Rome. Indeed, Livy says that:
The party structure would allow no
resolution to be made against such nobleman as justice would have
required. The Senate . . . . therefore passed examination of the
Celts' request to the popular assembly, in which power and
influence naturally counted for more. So it happened that those who
ought to have been punished were instead appointed for the coming
year military tribunes with consular powers (the highest that could
be granted).
The Celts saw this as a mortal insult and a host marched south to
Rome. The Celts tore through the countryside and several battalions
of Roman soldiers to lay seige to the Capital of the Roman Empire.
Seven months of seige led to negotiations wherby the Celts promised
to leave their seige for a tribute of one thousand pounds of gold,
which the historian Pliny tells was very difficult for the entire
city to muster. When the gold was being weighed, the Romans claimed
the Celts were cheating with faulty weights. It was then that the
Celts' leader, Brennus, threw his sword into the balance and and
uttered the words vae victis "woe to the Defeated". Rome
never withstood another more humiliating defeat and the Celts made
an initial step of magnificent proportions into history.

Other Roman historians tell us more of the Celts. Diodorus
Siculus notes that:
Their aspect is terrifying...They are very tall in
stature, with ripling muscles under clear white skin. Their hair is
blond, but not naturally so: they bleach it, to this day,
artificially, washing it in lime and combing it back from their
foreheaads. They look like wood-demons, their hair thick and shaggy
like a horse's mane. Some of them are cleanshaven, but others -
especially those of high rank, shave their cheeks but leave a
moustache that covers the whole mouth and, when they eat and drink,
acts like a sieve, trapping particles of food . . . . the way they
dress is astonishing: they wear brightly coloured and embroidered
shirts, with trousers called bracae and cloaks fastened at the
shoulder with a brooch, heavy in winter, light in summer. These
cloaks are striped or checkered in design, with the seperate checks
close together and in various colours.
The Celts wear bronze helmets with figures picked out on them,
even horns, which made them look even taller than they already
are...while others cover themselves with breast-armour made out of
chains. But most content themselves with the weapons nature gave
them: they go naked into battle . . . weird, discordant horns were
sounded, they shouted in chorus with their deep and harsh voices,
they beat their swords rythmically against their
shields.
Diodorus also describes how the Celts cut off their enemies'
heads and nailed them over the doors of their huts, as Diodorus
states:
In exactly the same way as hunters do with their skulls of the
animals they have slain...they preserved the heads of their most
high-ranking victims in cedar oil, keeping them carefully in wooden
boxes.
This page taken from http://www.ibiblio.org/gaelic/celts.html