>>727
The iron itself was a major factor, but so was the introduction of blades/ spear tips that were cast (i.e, mass-produced) instead of forged.
At least in Mycenaean Greece, the idea is that the highly-centralized palace-style economy could only support a small, elite military force; as having too many soldiers too far away from whatever regent you had invariably sparked rebellions.
Now guess what happens if you have some nomadic tribes who have a much larger number of soldiers by virtue that virtually every male owns a weapon and knows how to fight. And guess what happens if these guys just show up and ransack the local "palace" alongside the regent.
In a way, you could liken it to the end of the medieval age, when knights were increasingly replaced by better peasants armed with pikes, crossbows (and, most important) early gunpowder weapons. Heaving heavy armor and a lifetime of training didn't help when some random peasant could just dismount you from your horse with his pike or flatly shoot you in the face with a crossbow.
In the same way, the nomads with Iron weapons destroyed the small warrior elite of the palace culture by means of superior number and superior weaponry.
Depending on where the entire "hacking wars" thing might go, we may even see a new wave by means of collectivized regular citizens doing digital warfare against various government actors.
PS: In terms of weapons, the introduction of javelins also played a key role; as these could be lethal to the chariots many bronze age armies featured in lieu of cavalry with stirrups.