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...