Yeah, I would agree, Currency is definitely the best choice to Oracle. The Romans are so overpowered that crossbowmen and Great Walls can be easily supplemented with hordes of pretorians.
Here I conquered Persia from the off, as they had Babylon I left the Babylonians to collapse and went straight for the middle east. Later, when my army was poised to attack Eygpt they voluntarily vassalised, so I turned the army around and headed for India. I built the Pyramids ASAP this time so there's a lot more latin culture. Again, I had to add calendar in with worldbuilder to show off the date.
By the time Trajan came round his armies are busy pacifying Spain, Portugal, France, England, Belgium, western Germany, the Balklans, Greece, the Bosphorus, Asia Minor, the Magreb, the Middle East, Persia, the Caucaus, the Indus and Northern India, with a puppet in control of Eygpt.
It took a fair few Pretorians though...
EDIT
My Empire was barely clinging on by the end of the fourth century, the invasion of India had been halted at the last by lots of fortified axemen the wrong side of the ganges, and I screwed my economy by vassalising them before they collapsed. Constantinopolis had rebelled and been recaptured, but won't last for very much longer, ditto Spain and the Middle East. THe problem with running wealth in every city is no reinforcements, which was a bit tricky with no Great Wall. A lot more unstable this time as well, India was maybe a step too far. I actually had three or four spare settlers waiting around that I just couldn't afford to make cities with
Looks good on the surface,
but gets worse close up