1.4 The Classical World
- Both the Roman Empire and the Chinese Han Empire spread mainly toward their respective East and West, rather than to their North or South. Why is this relevant?
- What are the advantages of east/west empire expansion?
In this chapter, I want to talk about what I’ve called the third wave of globalization. That’s the classical age of the Roman Empire, its contemporaneous empire in China, the Han Empire and other geopolitics of that time. And I want to use this not to give a deep explanation of that history, but rather to illustrate the role of physical ecology in shaping what we look at as mainly geopolitics or imperial dynamics.
In fact, the empires of Rome and of China and many, many similar cases throughout history, are to a tremendous extent ecologically shaped in ways that perhaps are under-appreciated.
Let’s look at the Roman Empire at its maximum extent, roughly around 117 A.D. during the time of Emperor Trajan. And what you see is first of all, a characteristic of empires that might seem arbitrary at the start, but has a very deep base and that is that the Roman Empire lies mostly east-west.
The extent from the Atlantic coast in the west to the eastern Mediterranean is far greater than the north-south extent of the empire. And if you look at the map of the Roman Empire at its maximum extent and compare it to the climate zones that we have seen with the so-called Köppen-Geiger climate classification shown in the light green in this map, you quickly realize that the Roman Empire is almost defined by its climatology.
This is not surprisingly a Mediterranean climate. Remember that a Mediterranean climate is a subtropical climate that has the characteristic that it is cool, but not freezing in the winter months and quite rainy and warm and very sunny and typically dry.
And where Rome was able to reach and conquer was where the ecology supported the base of Roman life. What are the great crops of the Roman Empire? Well, wheat is the staple and wheat grows very well in exactly this Mediterranean climate. We think of this today as the Mediterranean diet with olive oil and the olive trees and that is the ecological extent of where the olive growing is. Most famous perhaps of all and most pleasurable is the winemaking, because wine is favoured by a Mediterranean climate.
Of course, not only in the Mediterranean basin, but also the Mediterranean climate of California, which is another example of a cool, wet winter and a dry, sunny summer in the Napa Valley of California.
And one can find similar ecological niches in Chile, on the west coast of South America or the west coast of Australia. And so the Roman Empire, one could say, in a way was defined by its wheat, its olives, and its winegrowing. Of course that’s not the only reason why the generals of the Roman Empire stopped their conquests at these boundaries.
To go south of that thin band of temperate zone of north Africa meant getting to the desert. The desert is a completely different ecology. It doesn’t support a high density population. It can’t support crop production, it introduces multiple new hazards. It requires camel-rearing rather than the horsemanship of the Roman Empire.
To go north of the Rhine and into the heavy soils of northern Europe and the much colder temperatures required technologies that were not available in Roman times. Heavier plows and new ways to farm and to clear very heavy forests that really wouldn’t be developed adequately for hundreds of years after the demise of the western Roman Empire.
So this east-west orientation is really a climate zone orientation, which in turn is an agro-ecological and a disease epidemiological orientation.
It is an animal husbandry orientation because this is a range where cows and where goats and sheep and horses familiar to the mixed farming of the Roman Empire could thrive. South and north, it becomes much more complicated. This pattern I want to insist is very common to empires throughout history.
Look at where they are, look at what their boundaries are. Lo and behold, there are reasons for those boundaries, why they didn’t extend north or south or into distinctive ecological zones.
We could take another look, in this case, at Alexander’s conquests which became the Hellenic age after Alexander’s death and then the division of his empire into successor states.
Look at its orientation. Again, this is an east-west orientation. It’s sharing a common ecological zone. It is an ecology where horses can play their military role, their transport role, where mixed animal husbandry in western Asia, in the Levant or the eastern Mediterranean, in Anatolia and western Asia, today’s Turkey, all can be part of a shared technological space of crops, disease burden, animals for traction and for mixed agriculture and for transport conditions, as well.
If we look at China, the Han Empire and look at the maximum extent of the Han Empire, what do we see? We again see an east-west orientation.
This is again, the subtropical and temperate climate, both the relatively warmer climates, but not in the tropics and avoiding the more poleward, cold climates that enabled China to thrive and to create a unified state.
China, of course, is a civilization that has been based on its great the rivers. With both the northern Yellow River and the more southern Yangtze River being the cradle of Chinese civilization. The northern zones, being more millet and wheat production, and the more southern farming areas around the Yangtze being rice cultivation.
But once again, one sees that China both in its ancient imperial history and up until today really bridges the temperate climate zones and its southern boundary, until today, is a tropical boundary, because the big distinction of today’s China and what’s sometimes called Indochina, the countries of Vietnam, Cambodia, Lao PDR, Myanmar, that southern boundary is the boundary to the tropical climates.
Distinctive agriculture, distinctive disease conditions, distinctive animal husbandry patterns, and though Chinese generals did several times try to invade and conquer, Vietnam, they never succeeded in doing so.
And one wonders whether part of the story was that they were fighting a climate as well as fighting a strong resistance from the Vietnamese throughout their history.
And that it was the ecology as well as the psychology that delimited the Chinese imperial areas. We can see in later conquests, both the Hun Empire, these are people from the steppes regions that created a huge land based empire north of the lucky latitudes, mainly in the steppe zones.
They became, of course, famed for their military valor and their capacity to conquer and to plunder in the waning days of the western Roman Empire.
But they are also an ecologically conditioned people, in this case, people of the steppes region. And the Huns of the 5th Century will be followed by the Mongols of the 12th and 13th Centuries as people of the steppe region with vast capacity to conquer based on a horse-based civilization that itself is inherently a grassland civilization.
The essence of a horse-based civilization is to be able to feed the horses and to have them in an ecological zone that they can survive. And that of course means plenty of pastureland for the horses and the great steppe regions. That is the so-called B climate zone that one can see in the climate map has defined the steppes of Eurasia and has given rise throughout history to periods of great military victory and vast but short-lived land based empires of the Huns, the Mongols, and similar populations from the steppe region.
Well, these are the east-west great empires sharing a temperate zone ecology, able to transmit agricultural technologies and other know-how, sharing other features of disease ecology and even mineral and physical geography that made it possible for Eurasia to become an integrated trading region already more than 2000 years ago.
And the great connector of that trade was the steppes of Asia, the grassland regions that supported horsemanship and horse-base transport.
These became the Silk Roads that linked Europe and Asia in history, that transmitted culture, technology, and armies throughout history. I think it’s right to say that up to and only until the invention of the steam-based locomotive and then the internal combustion engine in the 19th Century, the world’s highways were effectively the paths for horsemanship and horse-based transport.
And one could say that the steppes of Eurasia, the steppe lands, the grasslands of Eurasia were the great highway system that integrated Eurasia during the 2000 years, up to the modern age and up to the advantages that came with the ocean-based navigation, starting in the 16th Century.
Well, these are just snippets to give some feel for how the history of humanity, these great empires and their trade have these shapers of physical geography, of climate, of innovation and diffusion always for us to try to decipher and discern in our understanding of history, because these shapers of events continue in more recent history as I will now discuss in future chapters.