Kristina Cordero does well with the allusions and puns, but most readers would need a note on Fuentes's in-joke about C?r Aira becoming the first Argentine writer to win the Nobel prize and why another Argentine writer, Mart?Caparr?is turned into a killer. But there remains much to admire in this updated Liaisons Dangereuses, with its Mexican courtiers and courtesans.Jason Wilson is professor of Spanish at UCL. Contrary to popular imagination and Chinese tourist propaganda, the Great Wall of China did not exist continuously for 2,000 years, was never a single line of fortifications, and even failed to keep out invaders. English-speakers have been able to know this since Arthur Waldron's The Great Wall of China: from history to myth, but as specialists ruefully acknowledge, it will take a blockbuster of Wild Swans proportions before such "new" information becomes embedded as popular wisdom The Great Wall may be that blockbuster. The Great Wall we see today is a post-Mao restoration of a hugely expensive defence system built chiefly in the 16th century under the Ming dynasty.

Julia Lovell places this in the context of 3,000 years of varied Chinese frontier defences against the northern nomads of the inner Asian steppes. In a somewhat disjointed narrative (interspersed with capsule explanations of concepts such as the examination system), we see how Chinese policy alternated between defence and aggression, with walled fortifications, usually in discontinuous sections and often more than one layer deep, frequently playing a part in both. Walls built to reinforce the mountain passes leading into the North China plain tended to be defensive, as in the Ming. Those built far out in the steppe may have been bases for colonial occupation, as in the fourth century BC, before there even was a Chinese empire. Lovell attempts to do more than trace the changing functions of frontier walls.

She wants to use the variety of attitudes towards wall-building as a way of exploring the shifting relationship of Chinese governments to the outside world.This is a story of change and variety exciting enough not to need the sensationalist treatment (or the facetious tone) which the author sometimes adopts. It is becoming recognised that it is no longer enough to treat China as a monolith: unchanging, exotic, shockingly different. In the last generation, the isolationism of the Mao years has given way to an accelerating opening of markets and popular culture - though not of politics - to outside influences and foreign imports.In keeping with this dramatic shift, recent popular works have often rejected the idea of China as a "hermit kingdom" and instead emphasised the tendencies towards openness in past dynasties. Joanna Waley-Cohen's Sextants of Beijing traces the adoption of Jesuit and other ideas in the 18th century, while Valerie Hansen's Open Empire draws attention to an even wider range of earlier borrowings, not least Buddhism. (Less reputable are the claims of Gavin Menzies about Chinese cartography in 1421).Lovell is less optimistic.

Turning away from technology and culture to politics at the highest level, she finds openness only by treating Chinese imperial expansionism as a twisted form of internationalism. Her chief concern is with the efforts of successive dynasties to close out the threat posed by nomadic northerners. Here, Lovell's fascinating description of the variety of approaches to wall-building becomes mired in a set of persistent stereotypes that specialists have been working to debunk for a decade or more.To pursue her wider goal of examining the roots of the modern Chinese mindset, Lovell feels it necessary to maintain a sharp historical distinction between Chinese and non-Chinese. Since wall-building is her route into the twists and turns of Chinese thinking over three millennia, she argues that walls must be a uniquely Chinese solution to dealing with the neighbours.How, then, to explain why many non-Chinese regimes who ruled parts or all of North China and the southern steppe - notably the Jin dynasty, founded by the semi-nomadic Jurchen of Manchuria - also built walls? Why, by first becoming "sinicised" into honorary Chinese, of course. And how do you know that someone has become sinicised? Because they use Chinese methods, such as wall-building.The circularity of this outdated analysis obviates what could have been a much more interesting discussion of the foreign-relations complexities of China's "Middle Period" - roughly the 10th to the 14th centuries. Why, for instance, did the (non-Chinese) Jin build walls against their northern neighbours in the 12th century when their southern neighbours, the long-lasting (Chinese) Song dynasty, made little use of "long walls" despite being on the defensive against determined attack from the steppe?Explaining Jin wall-building under the rubric of "sinicisation" undercuts Lovell's own persuasive thesis that walls were used differently - or not at all - by defensive and expansionist rulers.