[Frank_2001]

If only the Huns had not attacked the Goths....and Rome had hung on just another three centuries...well they would have known what to do with Mohammed! ;)

[max americana]

“Rome had hung on just another three centuries...”

Rome couldn;t do it as the entire collapse of the empire was blamed on one thing: immigration.

Rome had to recruit from barbarian hordes to replenish it’s army and their cultures destroyed the empire slowly but surely. The new recruits were more loyal to their “other’ countries than to Rome and it applies today to us...

[rmlew]

If only the Huns had not attacked the Goths....and Rome had hung on just another three centuries...well they would have known what to do with Mohammed! ;)
If the Alan/Aryan confederation in the Pontic Steppe had not collapse. If the Goths in Crimea had held. If the Chinese had not allied with the proto-Manchus to crush the Hong-nu in Turkestan and push them West...
I'm not sure it would have mattered. Mohammed defeated the Arabs allied to the Eastern Roman/Byzantine Empire during the last and largest of the Roman-Persian wars. This 13 year conflict was fought from Egypt to Armenia, Thrace to Mesopotamia leaving both empires depleted. The Muslim exploded into this vacuum conquering Persia and the Levant within a generation. A unified Rome would have been able to recover from the loss at the Battle of the Yarmouk but the Caliphate would have existed.