[nuke rocketeer]

I seriously doubt that Ghengis Khan could have defeated an equal Roman army at the Empire's zenith. His greatest weakness was not having efective infantry. GK had the advantage of facing enemies with no effective and capably lead army. The Mongols were nothing but hit and run cavalry and the well organized legions of the early Roman Empire would have destroyed his army.

[Antoninus]

I seriously doubt that Ghengis Khan could have defeated an equal Roman army at the Empire's zenith. His greatest weakness was not having efective infantry. GK had the advantage of facing enemies with no effective and capably lead army. The Mongols were nothing but hit and run cavalry and the well organized legions of the early Roman Empire would have destroyed his army.

The Romans historically had great difficulty against mounted archers... How many Roman armies were destroyed in the wastes of Parthia? Crassus, Valerian, Julian, etc. Depending on the commander, the field of battle, and the usual intangibles though, I believe that the Roman army under, say, Trajan, could have successfully engaged and defeated Genghis.

[XJarhead]

Not exactly. Almost half of a Mongol umen was heavy cavalry capable of sustained combat. They'd have given the Romans some serious problems with the combination of missile fire followed up by heavy flanking charges. I mean, the Romans had a tough time with the Parthians, and the Parthians would have been no match for the Mongols. If the Romans had better archers or crossbowmen, it might be a different story.