You might make a point that the difference between the Norse attempts at North American colonization had rather more to do with the fact that they had arguably better hygiene, and no effective sets of civilizational plagues to bring with them, while the somewhat later to the table Portuguese, Dutch, and English brought with them the apocalypse in the form of diseases they’d long since grown immune to.

So… Did the Romans actually set the stage for the depopulation of the Americas? Did they go through a similar process, due to the communications they created within the Empire?

One does wonder what the results would have been, were they to have discovered the germ theory of disease earlier on. Imagine the Islamic conquests encountering an Eastern Roman Empire that wasn’t debilitated by the various plagues… Would Islam even exist, today?

I’m not so sure that Rome’s fall was really that harmful, over the long haul. Considering all the varied and many vices of Rome, not the least of which was their vicious destruction of neighboring cultures and civilizations (Trajan, I’m looking at you…) to loot them to the ground and enrich Rome, I’m really grateful we don’t have their national behavior surviving into the modern era. You contemplate a lot of what Rome actually was, in terms of culture? You’re going to be forced into a position of “Thank God they’re gone…”. The entire proposition of slavery, as they practiced it? The sexual values and mores that they saw as normal? The public violence of the gladiatorial games?

No, if you had a modern Rome as your neighbor, I’m pretty sure you wouldn’t be living in a happy nation. It wouldn’t be too far off from having a modern version of the Barbary States still in existence and raiding the coastlines of Europe for slaves and loot.