The harsh realities of Central Asian trench warfare as the Romans continue expanding in bursts and booms with developments in transportation and communication tech allowing greater and greater consolidation of what they have. Even the once mighty Persians are now only another saga told by Latin poets inhabiting a collection of provinces as Roman as Gaul or Germania Magna like the Carthaginians of old.

The wars narrow down to Samarkand as the two great empires tear apart the wide open landscapes of the Steppe to decide who will consume who.

The various Indian kingdoms have thrown in mostly with China knowing the tide is coming for them next, but Rome has made allies in Nusantara and Tamil country through the trade potential to all of them in cracking the jade egg.

China's already played their surprise card deploying their latest in gunpowder warfare technology, but the Romans have adapted in the most Roman way they possibly could, refining the digging process to allow soldiers to form a moving trench line that can crawl up against an enemy while allowing the soldiers to always be easily within cover. Roman propoganda now toutes the shovel as the symbol of Roman discipline and rank coordination.

With this stalemate an espionage operation is launched, two monks dispatched by the Emperor's secret order board a train bound for Nanqing. The Emperor has learned that the Middle Empire is transporting plans for the latest industrial marvel they've pulled out their asses to counter Rome's uncountable numbers. The monks are charged to seize the plans if possible, and make sure they never reach Nanqing if not.

Appropriately alt hist while also being a call out to a real heist that actually happened in real history, that being when Justinian ordered two monks to sneak into China, steal live silk worms, and make it back to Rome so that Rome could destroy China's monopoly on the stuff, and IIRC they pulled it off.