by Morris, Ian;
In the Han Empire, a much lower proportion of the population lived close to the sea or big rivers, and the rivers were in any case not always navigable. Rome’s military expansion secured a new economic frontier where farmers who applied the most advanced techniques to recently conquered lands could sell their crops to feed the cities of Italy and Greece, but in the absence of waterways like those of the Mediterranean, the Qin and Han conquests did this only on a much smaller scale. Some Han emperors worked furiously to improve transport by dredging the Yellow and Wei rivers and bypassing the worst stretches with canals, but centuries would pass before China solved the problem of not having its own Mediterranean Sea.
Two rather similar forces lay behind economic growth in both East and West, one pulling and one pushing the economy upward. The pull factor was the growth of the state. Roman and Han conquerors taxed vast areas, spending most of their income on armies along the frontiers (probably 350,000 troops in Rome and at least 200,000 in China) and gigantic capital cities (probably a million people at Rome and half that number at Chang’an, the Han capital). Both needed to move food, goods, and money from rich, taxpaying provinces to hungry, revenue-consuming concentrations of humanity.
Monte Testaccio (“Mount Potsherd”), a site in the suburbs of Rome, illustrates the scale of this pull factor in the West. This 150-foot-high, weed-covered mound of broken pottery is less dramatic than the Qin First Emperor’s tomb, but for hard-core archaeologists it is Italy’s answer to Egypt envy. Twenty-five million storage pots, a staggering number, were dumped here across three centuries. Most were used to ship olive oil—200 million gallons of it—from southern Spain to Rome, where urbanites put it on their food, washed with it,* and burned it in their lamps. To stand on Monte Testaccio is to feel awe at what hungry humans can do. And this was just one of Rome’s artificial hills of garbage.
The second force, which pushed the economy upward, was the familiar one of climate change. Global cooling after 800 BCE had thrown low-end states into chaos and set off centuries of expansion. By 200 BCE continuing orbital changes ushered in what climatologists call the Roman Warm Period. This weakened winter winds—bad news for farmers in the Mediterranean and in China’s great river valleys—but the high-end empires that had been created partly in response to the earlier global cooling now gave Eastern and Western societies the resilience not just to survive climate change but also to exploit it. Tougher times increased incentives for diversification and innovation. People tinkered with waterwheels and coal and exploited regional advantages by shipping goods around; high-end states provided roads and harbors to make these profitable and the armies and law codes to make profits secure, on the very sensible assumption that richer subjects will be able to pay more taxes.
High-end empires also pushed beyond the old heartlands into areas where the Warm Period made farming more productive—such as France, Romania, and rainy England in the West, and Manchuria, Korea, and central Asia in the East (Figure 6.3). Without knowing that they were doing it, the empires had effectively hedged their bets, since climate changes that hurt them in the warmer regions helped them in the cooler ones. In Rome, where the Mediterranean made it so easy for traders to move goods between regions, the benefits were surely huge; in China, where the great rivers were less convenient, the benefits must have been smaller, but real all the same.
The payoff from all the wars, enslavements, and massacres of the first millennium BCE was an age of plenty that inspired the Panglossian enthusiasm that opened this chapter. Its fruits were unevenly distributed—there were far more peasants than philosophers or kings—but more people were alive than in any previous age, in bigger cities, and on the whole they lived longer, ate better, and had more things than ever before.
When I began going on archaeological excavations, in 1970s England, I dug on several Roman sites. It could be exhausting work, clearing huge foundations of poured concrete (another Roman invention) with pickaxes and racing to keep the log books one step ahead of the flood of finds. But then I started doing a PhD on Greek society around 700 BCE, and in 1983 dug for the first time on a site of that date. It was a shock. These people just didn’t have anything. Finding even a couple of hunks of rusty iron was a big deal. Compared to earlier populations, Romans lived in a consumer paradise. Per capita consumption in what became the western provinces of the Roman Empire rose from a level near subsistence around 500 BCE to maybe 50 percent above it six or seven hundred years later.
Figure 6.3. Making the most of the weather: the maximum extent of the Han (c. 100 CE) and Roman (117 CE) empires, incorporating areas that benefited from global warming
Similar processes were clearly under way in the East, too, even if, as I mentioned earlier, they are not yet so well quantified. People in both cores remained desperately poor by modern standards—half of all babies died before their fifth birthday, few people lived past fifty, and poor diets typically left adults six inches shorter than us—but compared to all that had gone before, this was a golden age. Small wonder the ancient empires were crawling with Dr. Panglosses.
THE OLD WORLD EXCHANGE
What the Panglosses could not see, though, was how surging social development within the cores was also transforming the worlds beyond the empires’ borders. When empires were strong, they imposed their wills on the peoples along their frontiers, as when Darius of Persia in the sixth century BCE and the Qin First Emperor in the third brought great swaths of the central Asian steppe under their control; but when empires were weak, the nomads pushed back. In the West, the successor states that Alexander the Great’s generals built on the ruins of the Persian Empire after 300 BCE could never match the might of their illustrious predecessor, and Scythian raiders were soon plundering Bactria and northern India. Another central Asian group, the Parthians, began infiltrating Iran; and when the Macedonian kingdoms fell apart under the weight of Roman attacks after 200 BCE, the Parthians took full advantage.
The Parthians differed from earlier nomads who had pushed their way into the Western core. Nomads such as the Scythians got rich by robbing or extorting protection money from agrarian empires; they were basically bandits, with no interest in conquering high-end states and managing their bewildering bureaucracies. The Parthian horsemen, by contrast, were only seminomads. They came from the edges of the central Asian steppe rather than its barren heart, and had been living alongside farmers for generations. Their rulers knew how to extract taxes from downtrodden peasants while maintaining the horseback traditions that their military power depended on; and by about 140 BCE they had turned much of the old Persian Empire into a loosely integrated kingdom of their own.
The Parthian monarchs liked to call themselves the heirs of Cyrus and Darius and strenuously assimilated themselves to Western high culture, but in reality theirs was always a low-end state. It could never threaten Rome’s existence, although it did administer a short, sharp shock to any Roman who forgot the power of nomadic cavalry. Parthia’s horsemen were famous for the “Parthian shot,” where a rider pretended to flee, then turned in his saddle to loose arrows at his pursuer. Tactics such as these allowed Parthia to see off the Roman general Crassus, who lost his army and his life in a rash attack in 53 BCE. The Parthian king, a great admirer of Western culture, was watching a Greek tragedy when Crassus’ head was brought to him; his education was good enough that he could get the joke when the lead actor worked the grisly memento into his lines.
Rome’s problems with Parthia at the western end of the steppes, however, paled by comparison with China’s with the Xiongnu at the eastern end. There the Qin First Emperor’s preemptive war in 215 BCE had disastrous results: instead of intimidating the nomads, it set off a political revolution on the steppes, fusing the feuding Xiongnu tribes into the world’s first true nomad empire. Rather than taxing peasants to pay for a mounted aristocracy, like the Parthians did, the Xiongnu overlord Maodun funded his ultra-low-end state entirely by plundering China and buying the loyalty of lesser nomad chiefs w
ith captured silk and wine.
Maodun’s timing was excellent. He took over the Xiongnu in 209 BCE, right after the First Emperor’s death, and for nine years exploited China’s civil wars to loot to his heart’s content. In 200 BCE the first Han emperor, Gaodi, decided that enough was enough, and led a huge army into the steppe, only to learn that fighting nomads was different from fighting rivals for China’s throne. The Xiongnu fell back, letting the Chinese starve in the wilderness, and by the time Maodun turned and sprang an ambush, one-third of Gaodi’s men had lost fingers to frostbite. The Chinese emperor barely got out in one piece; and as generally happens in war, most of his men fared worse.
When he realized that attrition, inaction, and preemption were all failing against the Xiongnu, Gaodi came up with a fourth strategy: he would make Maodun family. Tearing his eldest daughter from Chang’an’s polished stone chambers and pearl-seeded bedspreads,* Gaodi packed her off to be Maodun’s wife, to count out her days in a felt tent on the steppe. A thousand years later Chinese poets still sang of the heartbreak of the Han maiden alone among the fierce horsemen.
This royal marriage initiated what Chinese scholars euphemistically called the harmonious kinship policy, and just in case love was not enough, Gaodi also bought Maodun off with annual “gifts” of gold and silk. Unfortunately the gifts did not really work either. The Xiongnu kept raising the price and then plundering anyway, confident that so long as the costs of the damage were less than the costs of going to war to punish them, Han emperors would do nothing.
Harmonious kinship lasted for sixty increasingly expensive years, until in the 130s BCE the Han court split bitterly over it. Some remembered the disaster of 200 BCE and urged patience; others bayed for blood. In 135 BCE, when his cautious mother died, the young Emperor Wudi joined the sanguinary crowd. Each year from 129 through 119 BCE he sent armies hundreds of thousands strong into the wilderness, and each year barely half their number returned. The cost in lives and treasure was appalling, and Wudi’s critics—the educated elite who wrote the history books—concluded that his preemptive war had been a disaster.
But Wudi’s campaigns, like those Darius of Persia waged against the Scythians four hundred years earlier (which were also judged a failure by the history writers), transformed the nomad problem. Deprived of gifts and plunder to share with subordinates and with their grazing lands under constant threat, Xiongnu rulers lost control of their allies and started fighting one another. In 51 BCE they acknowledged Han rule, and about a century later broke into two tribes. One retreated northward; the other settled inside the Chinese empire.
By the first century CE the Romans and Han had both gained the initiative against the nomads. The Han started “using barbarians to fight barbarians,” as they called it, giving the Southern Xiongnu a place to live (and constant “gifts”) in return for military service against other nomads. Rome, protected by the forests, mountains, and farms of eastern Europe from most movements along the steppe highway, only directly faced (semi)nomads in Parthia; and even here, Rome faced them not on the steppe, where nomads had so many advantages, but among the cities and canals of Mesopotamia. Whenever emperors got serious, Rome’s legions brushed Parthian resistance aside.
That said, neither Rome’s eastern nor China’s northern frontier ever entirely settled down. In 114 CE Rome chased the Parthians out of Mesopotamia, getting control of the whole Western core, only to abandon the land between the rivers in 117. Four more times in the second century Rome overran Mesopotamia, and four more times gave it up. Despite its wealth, Mesopotamia was just too far away and too difficult to hold. China, by contrast, found that bringing the Xiongnu inside its territory gradually converted its border from a line on a map into a fluid frontier zone, a Wild North where people came and went as they liked, the government’s writ rarely ran, and a good sword mattered more than legal niceties.
The growing entanglements of the nomadic and agrarian empires were altering Eurasia’s geography, shrinking the world just a little. The most visible consequence is a huge zone of shared material culture, stretching from Ukraine to Mongolia, through which merchants and warriors passed Eastern and Western ideas, art, and weapons from hand to hand. The most important cargoes moving between East and West, though, were ones that no one could see at all.
In the thousands of years since Old World farmers had started crowding into villages, they had evolved a nasty set of pathogens. Most were highly contagious; many could be fatal. Large populations breathing on one another and sharing body fluids spread diseases rapidly, but sheer numbers also meant that plenty of people happened to have the right antibodies to resist them. Over the millennia these people spread their defenses through the gene pool. Random mutations could still turn dormant diseases back into killers that would burn through the human population like wildfire, but hosts and viruses would then work out a new balance where both could survive.
People exposed for the first time to an unfamiliar package of germs have few defenses against the silent killers. The most famous example is what the geographer and historian Alfred Crosby has called the “Columbian Exchange,” the horrific, unintended fallout of Europe’s conquest of the New World since 1492 CE. Entirely separate disease pools had evolved in Europe and the Americas. America had unpleasant ailments of its own, such as syphilis, but the small, rather thinly spread American populations could not begin to compete with Europe’s rich repertoire of microbes. The colonized peoples were epidemiological virgins. Everything from measles and meningitis to smallpox and typhus—and plenty in between—invaded their bodies when the Europeans arrived, rupturing their cells and killing them in foul ways. No one knows for sure how many died, but the Columbian Exchange probably cut short the lives of at least three out of every four people in the New World. “It appears visibly that God wishes that [the natives] yield their place to new peoples,” one sixteenth-century Frenchman concluded.
A similar but more evenly balanced “Old World Exchange” seems to have begun in the second century CE. The Western, South Asian, and Eastern cores had each evolved their own unique combination of deadly diseases in the thousands of years since agriculture had begun, and until 200 BCE these developed almost as if they were on different planets. But as more and more merchants and nomads moved along the chains linking the cores, the disease pools began to merge, setting loose horrors for everyone.
Chinese documents record that mysterious pestilences broke out in an army fighting nomads on the northwest frontier in 161–162 CE, killing a third of the troops. In 165 ancient texts again talk of disease in the army camps; but this time the texts are Roman, describing pestilence in military bases in Syria during a campaign against Parthia, four thousand miles from the Chinese outbreak. Plagues returned to China five more times between 171 and 185 and ravaged the Roman Empire almost as often in those years. In Egypt, where detailed records survive, epidemics apparently killed more than a quarter of the population.
It is hard to figure out just what ancient diseases were, partly because viruses have continued to evolve in the past two thousand years, but mostly because ancient authors described them in such maddeningly vague ways. Just as aspiring writers today can buy books such as Screenwriting for Dummies then churn out movies or TV shows to formula, ancient authors knew that any good history needed politics, battles, and plagues. Their readers, like us when we go to movies, had a strong sense of what these plot elements should look like. Plagues needed omens of their approach, gruesome symptoms, and staggering death tolls; rotting corpses, the breakdown of law and order, and heartbroken widows, parents, and/or children.
The easiest way to write a plague scene was to lift it from another historian and just change the names. In the West the archetype was Thucydides’ eyewitness account of a plague that hit Athens in 430 BCE. In 2006, a DNA study suggested that this was a form of typhoid fever, though that is not entirely obvious from Thucydides’ narrative; and after other historians had recycled his (admittedly gripping) prose for a tho
usand years, not very much at all is obvious about the epidemics they described.
Despite this fog of uncertainty, Roman and Chinese sources contrast sharply with Indian literature, which mentions no plagues in the second century CE. That may just reflect the educated classes’ lack of interest in something as mundane as the deaths of millions of poor people, but more likely the plagues really did bypass India, which suggests that the Old World Exchange spread mostly across the Silk Road and steppes rather than by the Indian Ocean trade routes. That would certainly be consistent with how the epidemics began in China and Rome, in army camps on the frontiers.
Whatever the mechanisms of microbial exchange, terrible epidemics recurred every generation or so from the 180s CE on. In the West the worst years were 251–266, when for a while five thousand people died each day in the city of Rome. In the East the darkest days came between 310 and 322, beginning again in the northwest, where (according to reports) almost everyone died. A doctor who lived through the sickness made it sound like measles or smallpox:
Recently there have been persons suffering from epidemic sores that attack the head, face, and trunk. In a short time, these sores spread all over the body. They have the appearance of hot boils containing some white matter. While some of these pustules are drying up a fresh crop appears. If not treated early the patients usually die. Those who recover are disfigured by purplish scars.
The Old World Exchange had devastating consequences. Cities shrank, trade declined, tax revenues fell, and fields were abandoned. And as if all this were not enough, every source of evidence—peat bogs, lake sediments, ice cores, tree rings, strontium-to-calcium ratios in coral reefs, even the chemistry of algae—suggests that the weather, too, turned against humanity, ending the Roman Warm Period. Average temperatures fell about 2°F between 200 and 500 CE, and since the cooler summers of what climatologists call the Dark Age Cold Period reduced evaporation from the oceans and weakened the monsoon winds, rainfall declined as well.
