Goods, Germs And Ideas On The Silk Road

AThe Silk Road of the popular imagination is a highway of luxuries, and that image is not so much wrong as badly weighted. Museums are full of the things that travelled it, or are believed to have done: patterned silks lifted from dry tombs, glass bowls, coins struck two thousand kilometres from the place where they were finally buried. What no museum can display is millet, dried curd, felt, firewood or salt, because such things are eaten, worn out or burnt, and a cargo that leaves no residue leaves no reputation either. The imbalance is not merely a matter of display. It shapes the questions that get asked, since a historian who begins from an inventory of surviving goods will end by explaining the movement of goods and nothing else. Volumes are reconstructed from objects, so a trade in imperishable rarities gets counted while a trade in perishable staples does not, and the resulting impression, drawn most memorably in a general history of 1938 and copied ever since, is of a thin line of caravans hauling treasure across an empty continent. Whether that impression can withstand contact with the rubbish left by the people who actually used the routes is the question that has occupied the past two decades of fieldwork.

BAnneke Roelofs, an environmental historian at the Utrecht Institute for Historical Ecology, has spent much of that time in the waste pits of oasis settlements. Between 2011 and 2018 her team sorted 6,700 identifiable seeds from twelve pits at Turfan and Kucha, dating each layer by the charcoal lying above and below it. Rather more than seven-tenths of the plant remains came from crops grown within a day's walk of the town, and most of what was left came from valleys three or four days away. Genuinely distant material was scarce: cotton from the south turns up in 3 per cent of samples, and pistachio from the west in barely 1. The dating is coarse, she admits, because charcoal can be older than the pit it lies in, though the proportions hold across all twelve deposits and across the whole span they cover. Roelofs argues that this is precisely what a relay system ought to look like, with goods changing hands often and travelling far, yet with each settlement living, week by week, on what its neighbours grew. Long-distance luxuries, on her reading, rode on the back of a dense local commerce that has left almost no mark on the histories.

CThe waste of those same settlements has yielded something less expected. Latrine deposits at two relay stations contain the eggs of a liver fluke whose hosts live only in the wet lowlands at the far eastern end of the continent, and the layers holding them were laid down between 1180 and 1290. Nobody transported a fluke on purpose; it arrived inside somebody who had walked, or been carried, a very long way. Roelofs maintains that the corridor shifted organisms at least as efficiently as it shifted objects, and that this movement stayed invisible for centuries precisely because it required no cargo at all. Two deposits are a slender basis for any general claim, and she does not pretend otherwise, but no rival explanation has yet been offered for how an eastern parasite reached a desert town. She is careful about scope. The eggs came only from stations on the northern, better-watered branch, where parties halted for several days at a time and drinking water was shared; along the drier southern branch, where stops were brief, no comparable deposit has yet been found.

DBruno Estival, an epidemiologist at the Ghent Centre for Comparative Disease History, doubts that movement on this scale could have carried much of anything. Working from tax registers and the capacity of the known caravanserais, he estimated in 2020 that no more than 240 travellers a year crossed a typical northern pass in the thirteenth century, a figure far below the level at which his transmission models will sustain a chain of infection. A parasite in a latrine, he insists, records one journey and not a route in regular use. Estival's own assumptions have since been questioned. His party sizes are taken from nineteenth-century caravan accounts and may understate medieval traffic by a wide margin; his registers leave out pilgrims, soldiers and the herders who moved with their animals every season; and he concedes that a single infected traveller can seed a settlement in which transmission afterwards continues locally, which blunts the threshold argument he depends on. None of this shows that his estimate is wrong; it shows only that the margin of error around it is wider than the figure itself suggests.

EWhere the two accounts converge is on technique. Paper-making, cotton dyeing and the casting of certain bronzes appear in western oasis towns within a century of appearing in the east, and in each case the archaeological signature is not a traded object but a workshop: kilns, moulds and the debris of the process itself. Skills, unlike silks, cannot be loaded onto an animal; they travel only when the people who hold them settle and take apprentices, which happened where a local ruler was prepared to pay for it and hardly at all where nobody was. That condition accounts for the distribution better than the quantity of goods does, and it points towards a modest conclusion. The routes mattered less as a channel along which valuable things flowed than as a mechanism by which organisms, crops and craftsmen were occasionally relocated, and the consequences of those relocations outlasted every bale of silk that ever reached the Mediterranean. The romance, in other words, was never in the freight.