[quote=@Thang] Well, the Eastern Roman Empire fought Islam didn't it? Came off pretty bad if I recall. In fact, didn't we send the Crusaders over, because the Byzantine Emperor was like "yo, we're losing, and when we lose, then you Catholics are gonna get a face full of Islam"? But yeah, the idea of a Western Roman Empire, or indeed, a totally Unified Empire (No Byzantium) would be interesting. I did a lot of research into the how the western Empire fell; poorly managed multiculturalism was a big factor, if memory serves. Also the whole pagan vs Christianity thing went down like a boat on fire full of orphans. Your best bet, to make it simple, but also credible, is to inject a highly competent Western Emperor in 300-400 A.D who managed to reverse Rome's fortunes, stabilize the frontiers and the flagging economy, and who through political means reunited Rome with Constantinople. That way you haven't got to read through tonnes of history books to grasp the finite details of what went wrong, and why. EDIT: Unless that's what you want to do; may take you a while though. In any case, I'll keep an eye on things and see how they develop. [/quote] The fall of Rome was complicated, but the rapid fall of the West in the 5th century seems to mostly have been a mix of highly incompetent Emperors combined with how so much of its borders faced the German north, which had been destabilized by rapid migration from the east. There had been competent Emperors in the fourth century, Theodosius was quite capable and held the entire Empire together up until 395. I'm not sure what could be done to change the course after him though. Perhaps Flavius Aetius or Stilicho are Emperors, or maybe Honorius decides to man up and do his job? We'd have to come up with some excuse. By the time that the west fell, the Christianity vs Paganism thing was already more or less settled though, so I don't think that would be an important situation. We'd be seeing the theological problems of the time still shine through. Probably Catholic Orthodoxy vs Monophysites. However, even with a competent Emperor at the helm, a complete Roman Empire that survives until the 7th century would be dragging itself along stretched thin and bloody. It wouldn't be Augustus's Rome, this would be a state permanently teetering on civil war and facing invasion on all sides. You might see Britain fall to the Saxons despite Roman success on the continent, and by the 7th century Europe would be facing invasion from Franks, Lombards, Slavs, Avars, and Bulgars. In this environment, the sudden explosion of Islam could still be incredibly dangerous to even a unified Rome. The reason I think it would be interesting is that it has this quality of being between the ancient world and the medieval. It is a world where there are knights and proto-feudal nobles on the frontiers, but there is also a very ancient quality to education and bureaucracy. You would still see standing armies led by generals with political ambitions, and noble children learning their Aristotle and Plato, and big cities full of seething masses who are so obsessed over Chariot races that whether you are a "Blue" or a "Green" plays a part in absolutely every part of daily life, right up to Imperial politics. It is true that this all happens to be the case with the Byzantines as well, but there is something more grandiose about including the entire Empire, and it allows us to go our own way. There is always something defeated feeling about the Byzantines, like they are the Rome that lost it all but stubbornly refused to jump off the boat. They switch to Greek, and after Justinian dies they become very regional in their politics so that it is clear the rest of Europe no longer belongs in their sphere.