Who can prove when the Marian reforms happened?

[Somebody Else]

I would say sometime in the few years after the battle at the Arausio River, where - through inept leadership, 80,000 Romans were slaughtered, in 105 BC and the battle of Aquae Sextiae in 102 BC, where the new Roman army had it's revenge on the Germans.

Marius was consul from 104-100 BC, so I would imagine the reforms took place during this time period.

In game - it could be any time from 104 to 102 BC I reckon.