FOR A MAN who was believed to set the greatest store by divine guidance and to live his life according to the dictates of Eternal Heaven, Genghis Khan apparently had rather earthy preoccupations. Writing half a century after Genghis’s death, the Arabic historian Rashid ad-Din tells the following story about the Mongol conqueror. Genghis had been out riding with his general Boorchu and other comrades in arms and had asked them what they considered to be man’s greatest happiness. Being twelfth-century Mongols, they told him it was falconry. Not so, replied their leader:

Man’s greatest good fortune is to chase and defeat his enemy, seize all his possessions, leave his married women weeping and wailing, ride his gelding, use the bodies of his women as night-shirts and supports, gazing upon and kissing their rosy breasts, sucking their lips which are as sweet as the berries of their breasts.

The passage probably says as much about Rashid ad-Din’s lustful thoughts as it does about Genghis, but it is in keeping with his enduring popular image as the ultimate warlord, the rapist’s rapist and the pillager’s pillager. Razing all before him, he reveled in destruction and bloodshed as he annexed an empire which at the time of his death in 1227 stretched from the Pacific Ocean to the Caspian Sea. Cruelty and conquest were simply two sides of the same coin. This is, of course, something of a caricature, and one whose inaccuracies John Man is eager to correct in this popular history and travelogue. Genghis was a subtler figure by far, possessed of genius, convinced of his divine calling to subdue and rule an unruly world. ‘This was no mere political stance,’ Man writes; ‘I think he believed it heart and soul.’

This unbreakable faith in his heavenly support, Man argues, created a division within Genghis between the arrogance required in a man determined to unite his people and lead them out of their homeland to conquer the world and ‘the humility of an ordinary man awed by the inexplicable nature of the assignment’. Personally, I’m not sure such a conjecture, which takes the official Secret History of the Mongols at face value, is all that helpful, and it is not supported by much hard evidence either.

If one looks at motives for world conquest there are obvious parallels with Tamerlane, Genghis’s fourteenth-century counterpart and, in my view, a greater and more complicated figure by some margin. Like Genghis, the Tartar conqueror was apt to stress the divine nature of his mission, not least before crucial battles, when he was wont to pull out a copy of the Koran and open it at a conveniently auspicious passage auguring the defeat of the enemy infidels. Did he really believe it? It is difficult to say, but considering the priority he gave to expedience in all matters – whether military, political, economic or sexual – it seems unlikely. Generally speaking, and at the risk of oversimplification, his policy was to use whatever worked best.

Genghis and Tamerlane both saw themselves as bringing peace to a chaotic world. But, as Gibbon remarked in a characteristically dry aside on the Tartar, ‘the remedy was far more pernicious than the disease . .. Perhaps his conscience would have been startled if a priest or philosopher had dared to number the millions of victims whom he had sacrificed to the establishment of peace and order’. I wasn’t convinced, either, by Man’s ch that one of Genghis’s ten policies was to oppose cruelty. Like Tamerlane he used terror for his own political and military ends, above all to drive fear into his enemies’ hearts and punish disloyalty among his own followers. It may not have been cruelty for cruelty sake but in his methods he was hardly squeamish, even by the standards of his age.

Genghis’s story, of course, has been well rehearsed before. My own favourite version, admittedly a little old-fashioned, is Harold Lamb’s Genghis Khan: The Emperor of All Men, published in 1927. Lamb manages quite brilliantly, without resorting to the travel writing which Man employs, to evoke the toughness and romance of twelfth-century life on the steppes of Eurasia. There is an exciting immediacy about the book, which is not necessarily true of this latest, alternately more scholarly and more whimsical, study. I missed the sense of the fury of Genghis’s battles and the sheer whirlwind of his conquests.

Man, however, is an excellent guide to a subject which can be fairly impenetrable for those not familiar with the culture, geography, people and places of Central Asia and the Far East. Well versed in Mongolian, he has travelled extensively in the country while researching the more mysterious elements of Genghis’s life, and this experience shines through the book. He is able to trace cultural continuities from the twelfth and thirteenth centuries into the present day which would escape other writers less familiar with the terrain. He writes knowledgeably about the Mongolian diet, national character and traditions of horsemanship, and these apparent digressions in fact make illuminating passages.

At other times, however, the travel writing is a distraction from the task at hand. We don’t need to know that the author watched the World Cup final between Brazil and Germany in a wooden shack in the heart of Mongolia: travellers can do that sort of thing anywhere in the world these days, and in any case it is banal.

I braced myself for the inevitable disappointment when Man set out to discover, albeit without great hopes of success, Genghis’s notoriously elusive burial place. Was a British travel writer-really going to come up with the goods where so many others had failed? Of course not. To this reviewer it had the unfortunate aftertaste of Tahir Shah’s similarly hopeless quest for King Solomon’s mines. That is probably a little mean, given the profound enthusiasm behind the mission, but devoting a full third of the book to life after Genghis seems too much.

That said, where Man is particularly effective and interesting is in his discussion of how Genghis has been used by both the Chinese and Mongolian states over the years. In 1962. the 800th anniversary of Genghis’ birth, the sponsor of a ten-metre statue of the conqueror ended up getting fired from his job and sent into exile. In Soviet eyes, Genghis was a barbarian villain. The Chinese regard him as founder of the Yüan dynasty and therefore part of Chinese history. The Mongolians inevitably feel rather differently, claiming him as their great national symbol. Again, there are instructive parallels with Tamerlane, a figure for years vilified by the Soviets, but latterly resurrected by independent Uzbekistan as symbol of the new nation.

Hero worship of Genghis Khan, as John Man concludes, has now reached unparalleled heights. Today he is a demigod in his own right, the heart of one of the world’s more outlandish cults. Perhaps he would have expected nothing less.