Persian Empire

[dake]

Im quite new to EB have only tried out the factions abit no longer campign. But i was wondering about the persian reforms? When they occour those my faction change from ex Pahlava into the Persian Empire (as Arverni,Aedui into Gallic Confederacy) or do i only gain some access to new units and buildings?

I wonder if any faction is able to create the persian empire triggering the reforms or is it just Pahlava? I suspect the Haysadan might be able to but perhaps im wrong.