For half a millennium the empire of Rome stretched from Hadrian's Wall to the river Euphrates, a massive fortified state founded on military might and the pillars of civilization - writing, the city, and the rule of law. But beyond these frontiers lay other lands, the lands of seemingly anarchic warrior tribes, the land of the Barbarians.

The opening scenes of 'Gladiator' are based on the victories of Marcus Aurelius over one such tribe, the Marcommani. Two hundred years later the Romans still seemed invincible, routing 30,000 Alamanii at the battle of Strasbourg. However, within a generation, the foundations of this order were shaken to their core, and Roman armies, as one contemporary put it, 'vanished like shadows'.

What had happened? Covering the last 100 years of Empire, a period full of great battles, treachery, and characters as wild as Attila the Hun, Peter Heather shows how the Empire gave way before the relentless and deliberate onslaught of the Huns, Goths and Vandals. These tribes, originating in Eastern Europe, finally conquered large tracts of the old Empire, sacking Rome itself and defeating Roman armies on land and sea.