In the thirteenth century, the Mongol khans sent their armies swarming across Europe. They pillaged Poland and Hungary and it seemed a matter of time before they reached the Atlantic. But then news came of the death of the great Khan Ogedei, and they returned to Mongolia. In his new book, Stanley Stewart examines the countries the Mongol empire created. Travelling first through the fracturing southern republics of the former Soviet Union, the heart of his journey is a 1,000-mile ride through the Mongolian steppe, culminating at the site where Genghis Khan is thought to be buried. Frequently changing guides and horses, Stewart's journey reveals a country where an eroded form of modernity is slowly closing in on the medieval customs bequeathed by the khans.

Stewart is at his best describing Mongolia's otherworldly scenery. When writing about the crags, valleys and emptiness, his prose has a poetic resonance that creates a powerful impression of his experience. His characterisation is pithy, but, in seeking to force as much humour as possible, it can appear patronising: two Russians illustrate why Slavic women cannot find 'any middle ground between slim grace and stout coarseness'.

Nevertheless, Stewart writes with knowledge and insight. The trigger of his journey, he tells one librarian, was a fascination with nomads, people whose only commitment is to movement. 'But the movement is only physical,' the librarian replies. And it is this, Stewart writes, which explains the preservation of Mongol traditions - the result of continous movement was a culture where many traditions remain from Genghis Khan's day.

• Toby Green, a former finalist in The Observer Young Travel Writer competition, is the author of 'Saddled with Darwin'(Phoenix House), which was shortlisted for this year's Thomas Cook Award