By the 5th century BC vigorous tribes are speading outwards from their original homeland east of the Rhine, in places such as Hallstatt and La Tène. With the advantage of iron weapons, they are able to press east into the Balkans and west into France and Spain. Considerably later, in about 300 BC, they cross the Channel to Britain. They are the Celts.
The Celts are great story-tellers, great drinkers and great fighters - with a liking for single combat, after which the victor proudly displays the severed head of his opponent. Soon they begin to trouble their very different neighbours, the sober and disciplined Romans.
The Celts push south through the Alps, raiding and marauding. In about 390 they even reach and sack Rome. Many of them stay in Italy, settling in an area from the Alps to south of Milan. The Romans call them Gauls, and distinguish their two nearest territories as Cisalpine Gaul ('this side of the Alps', as seen from Rome) and Transalpine Gaul ('across the Alps').
Much of Cisalpine Gaul comes under Roman control after a campaign in 225, but the Celts here remain unreliable; a few years later many of them side with Hannibal. Beyond the Alps, southern Gaul becomes a Roman province in 121. The rest of Gaul escapes the grasp of Rome until the arrival of Caesar.
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