Why the Eastern Empire outlasted the Western Empire

There are many reasons for the Byzantine Empire outlasting the Western Empire: geography, Greek Fire weaponry, leadership, diplomacy, etc. (See the link below). This short video emphasizes the geographic military advantages of Constantinople:

https://historycollection.com/7-reasons-byzantine-empire-lasted-long/3/

The Eastern Roman Empire had the most urbanized and richest provinces.

This was a product of the fact that most Classical Greek cities were in the Eastern Mediterranean; below is a map with the ca. 900 Ancient Greek city-states in which we know their geographical location (POLIS (stanford.edu)); notice how the regions populated by a large number of Greek cities closely matches the territory of the Byzantine Empire around the year 1000:

While Romanization resulted in significant development in the Western half of the Roman Empire, it is still true that the Western half never reached the same degree of development as the Eastern half. Hence, when the Roman Empire was broken into two halves, the most developed half lasted a thousand years longer.

I wouldn't think it is particularly due to Constantinople being hard to conquer, while it being a fortified bastion helped to deter critical attacks; it's also true that the Byzantines held over much more land than just Constantinople for most of the thousand years they outlasted the western empire. So, I think the East's survival was mainly due to a combination of being:

(1) Having more developed lands that could pay more taxes, so they were capable of supporting more, better trained, and equipped soldiers.

(2) These lands were in strategic positions that were more defensive (in particular, the city of Constantinople, but also the provinces of the Eastern Roman Empire had a smaller frontier with the northern European tribes. And the Sassanid Persians, despite their historical enmity with Rome, were a bit less dangerous than the Northern European tribes (in my evaluation).

North Africa was the most heavily urbanised part of the Roman Empire. 

I am actually working on a scientific paper regarding urbanization levels across the Roman Empire and Classical Greece. My methodology is based on archeological evidence. My conclusions so far:

1) The Classical Greek world was substantially more urbanized than any region of the Roman Empire (but the difference in rates of urbanization was smaller than estimated before, Roman Greece in particular was almost as urbanized as Classical Greece).

2) Roman Greece and Greek-speaking regions of Crete, Sicily, Cyrenaica, and the western part of Asia Minor were the most urbanized.

3) The ranking of urbanization rates by region is the following:

1. Mainland Greece, Sicily, Crete, and Cyrenaica (most urbanized)

2. Italy

3. Egypt (it was very urbanized, possibly be more urbanized than Italy)

4. Asia Minor and North Africa (roughly the same rate of urbanization in both regions, however Asian Minor population estimates include large rural populations in the interior of the region)

5. Syria

6. Gaul

7. Balkan provinces north of Greece, bordering the Danube

8. Iberia (surprisingly, it is mostly not urbanized although there were many cities in Baetica)

9. Britain (least urbanized)

Rates of urbanization are estimated in terms of the proportion of the population living in cities with at least 5,000 inhabitants (smaller towns like Herculaneum and Priene do not count as urban by this method, but I had to use a high cutoff because archeological information regarding smaller towns is very incomplete). About 1/6 people in the Roman Empire lived in such larger towns and cities, with nearly 1/4 or 1/3 in the most urbanized regions and 1/20 in the least urbanized regions.

This is a map of 885 surveyed Roman cities scaled by the estimated size of their geographical areas, which I used to make my estimates:

Out of the 15 biggest cities among those cities with measured areas, 12 were Greek cities (often Hellenistic colonies), while 11 were in the Eastern Provinces and 4 were in the Western Provinces.

In terms of East vs West, the rates of urbanization are not that different because Sicily, North Africa, and Italy were highly urbanized. While Gaul, Iberia, and Britain were not very urbanized.

5 hours ago, Guaporense said:

I am actually working on a scientific paper regarding urbanization levels across the Roman Empire and Classical Greece. My methodology is based on archeological evidence.

Interesting research. I would like to see your results. I guess it would depend on the time period examined. Constantinople wouldn’t be among the largest population centers until the fourth century AD, for example.

I’m surprised to see Hispania listed as among the least urbanized considering Cadéz and Córdoba were large urban centers. 

Please share your research.

My study is for the Early Roman Empire around 100 AD.

Iberia was not heavily urbanized, considering it did not have many large cities compared to the size of the Iberian Peninsula. Archeological surveys suggest that Sicily had a comparable urban population to Iberia.

I have used demographic estimates by Scheidel (2009) adjusted with other references (he appears to overestimate the population of Roman Iberia, considering the small urban population and other sources yield more conservative estimates for the Iberian population). Overall the Roman Empire had 65 million, excluding client states/provinces like Bosphorus, Armenia, Dacia, and Mesopotamia.

Iberia was indeed huge, so its total population could not have been much smaller than around 5-6 million. Hence, its overall rate of urbanization was certainly pretty low compared to the rest of the Roman Empire.

According to this framework, the city of Rome had 923,000 inhabitants, which can be thought of as slightly lower than typical estimate for Rome (about 1 to 1.2 million).For Pompeii, my estimate is 8,900 people, which is also slightly lower than the typical estimate around 11,000 to 12,000.

Overall, according to these estimates, you had about 35 million people in the Western Half of the Roman Empire and 31 million in the Eastern Half. The urbanization rate was slightly higher in the Eastern Half, 17%, versus 15% in the Western Half. So perhaps the difference in development (as indicated by urbanization rates) between the two halves was not large enough to explain alone why the Eastern half of the Roman Empire lasted longer—the fact it was more defensible also important.