But to create a new legion, you must control its historically native province, like Latium for Legio I Italica. You can restore ancient legion system and form 11 legions! Each legion has up to 6 thousand legionnaires, so you can defeat both the Mongols and the Aztecs alone. But be sure, this will provoke a civil war. You can overthrow republic and proclaim an empire! For that, you need to have a loy of money and prestige, and Republic must have an Empire tier. Pope, begone!) and be a christian or hellenic pagan. You can now restore Roman Republic as any merchant italian (or greek, like Amalfi) republic! For that, you need to control most of italian lands (and Rome, of cource.