It almost goes without saying that Shadow of the Silk Road is an exquisitely written book. Colin Thubron is a grand master of the travel genre, and his prose is unfailingly poetic and evocative. By virtue of his pen, mountain peaks float like "astral ice-fields", deserts open into "camel-coloured voids" and rivers of "liquid loam roil" between gullies.
The human landscape through which Thubron travels is equally haunting. Making his way along a staggering 7,000 miles of the so-called Silk Road, he passes through the shadows of dozens of empires and civilisations that have risen and receded into the sands, leaving a detritus of human history scattered along the way.
Thubron's account of his epic, eight-month journey, which begins in Xi'an, in China, and progresses west to Antakya on the Turkish Mediterranean, taking in many of the central Asian "stans" and Iran along the way, makes clear that the glory of the Silk Road has long since faded.
For thousands of years, the Silk Road was a complex and sophisticated entity: a vast network of arteries that branched across the breadth of Asia, nourishing the societies it touched with new ideas, inventions and exotic commodities from distant lands. Silk was just one Chinese export that percolated along the ancient "road" to India, Persia and beyond. As Thubron points out (placing in sharp historical perspective the modern-day "rise" of China), the Chinese were busy inventing things such as paper, gunpowder and compasses while barbarians in Europe were struggling to heat their caves.
Eventually, such carefully preserved secrets found their way west, taken from caravanserai to caravanserai, from merchant to merchant (although, in the case of paper, this didn't happen for a staggering 1,200 years after its invention). The heavy stirrup did not emerge into the wider world until long after it was dreamt up by the Chinese in the 4th century AD. When, at last, it reached the west, the impact was immense. As Thubron puts it: "To this simple invention some have attributed the onset of the whole feudal age in Europe."
The traffic wasn't one-way. "The caravans that lumbered out of Chang'an [Xi'an] - sometimes a thousand camels strong - went laden with iron and bronze, lacquer work and ceramics," Thubron continues. "Those returning from the west carried artefacts in glass, gold and silver, Indian spices and gems . . . and the startling invention of chairs." This went for religion, too. The Silk Road served as a superconductor for Buddhism and Islam as it spread east. And it carried people as well. Slaves, nomads, pilgrims, merchants and countless armies trod its path, many entirely forgotten by history.
The most fascinating episodes in the book come when Thubron encounters these "lost" peoples. He tracks down Chinese with blue eyes and big noses, believed to be descendants of 10,000 Roman legionaries who went "missing" in 53BC. And later, on the edge of the Taklamakan, the "most dangerous desert" in the world, he is shown perfectly preserved, 3,000-year-old mummies with Aryan features, dressed in "Celtic-looking tartans" and "witches' hats". How these European-looking people came to settle in China is a mystery, but their discovery suggests that human movement in the ancient world was more fluid than we have previously imagined.
Today, the lands through which Thubron tramps are less travelled than perhaps at any time in history. The camel is all but redundant. Goods pass overhead at 25,000 feet. And despite the region's mineral wealth, central Asia has receded into an economically, philosophically, spiritually and artistically stagnant state comparable to that of Europe during the Dark Ages. Cities such as Herat and Samarkand, once great seats of learning that nurtured human thought, are mere cultural and physical husks. The impetus that drove this region centuries before the rise of the west has evaporated.
Everyone the author meets along the way seems to be reeling from this cultural meltdown. Thubron is clearly a sympathetic soul and, as a foreigner with no vested interests, he finds himself playing priest to the confessionals of the downtrodden, the persecuted and the plain frustrated. In the frontier city of Kashgar, he meets Uighurs who complain bitterly about the Chinese invasion of their lands. In Turkmenistan, he finds a society whose spirit has been crushed and depleted by communism. In Tehran, where he goes to a rock concert, young people rail against the ayatollahs.
Ultimately, Thubron doesn't attempt to delve into what ails the cultures he visits. He is content to describe what he finds and marvel at the past. At times, he can be stubbornly western. While visiting the tomb of Omar Khayyám in Nishapur, he lauds Edward Fitzgerald's translation of The Rubáiyát, failing to appreciate that the original contains an essence entirely lost in English. But on other levels, Shadow of the Silk Road is a towering achievement, a journey as rare as the exotic goods that merchants once plied along the Silk Road itself. The history he skilfully weaves through his narrative testifies to the vastness of human potential and the inestimable power of new ideas. Sadly, it also serves as a reminder of how prone we are to forget and stagnate.
Tarquin Hall is the author of "Salaam Brick Lane: a year in the new East End" (John Murray)