When anyone claims, as official histories do, that China has never invaded another country, there is some harmless amusement to be had in asking why, if so, the Great Wall is in the middle of the country? From the 14th century, the Ming dynasty Jade Gate fort, now in the province of Gansu, marked the western limits of civilisation. Beyond, as David Eimer reminds us in The Emperor Far Away: Travels at the Edge of China, lay demons, wind and emptiness. These phenomena are now incorporated into today's enlarged China, along with approximately 100 million non-Han citizens who live for the most part along China's 22,000 kilometres of land border, looking across the frontier at any of China's 14 neighbouring states. These include the Kim dynasty's North Korea, post-communist Mongolia, the post-Soviet "stans" of Central Asia, Myanmar, Vietnam and Russia, most with ethnic counterparts on the other side of the China border. Then there is India and its old enemy Pakistan, and a short border with Afghanistan. Eimer has travelled around much of this vast periphery, and has written an ambitious if uneven travel book that serves as a useful reminder that China is vastly more than the well-trodden eastern seaboard.

The Emperor Far Away is published by Bloomsbury (£20). Click here to buy it for £16 with free UK p&p