Iron-using warriors established tribes in Central Europe, North of the Alps. The Celts came to Ireland around 700BC. Since the Romans never invaded Ireland, Celtic tradition was allowed to develop there uninhibited by Christianity for hundreds of years more than on the European mainland.

The Celts also wreaked havoc with the Holy Roman Empire. In 386 BC, the blonde barbarians blasted through the streets of Rome, driving all surviving inhaitants scurrying up Capital Hill. The Celts, unable to get over the Capital's fortified walls, waited at the foot of the hill for no less than seven months, until the rotting stench of the decomposing corpses littering the battlefield caused many of them to be ill. They finally agreed to go away for a tribute of 1000 pounds of gold, a sum which the city found great difficulty in amassing. When the gold was ready to be weighed, the Romans accused the Celts of using faulty weights. Brennus threw his sword into the laden balance and uttered the words, "vae victis", woe to the defeated. It was the worst humiliation Rome had suffered in her history.