Yunnan has always stood apart from the rest of China, set high on the empire's "barbarous and pestilential" southwestern frontiers and shielded from the rest of the nation by the unruly, mountainous provinces of Sichuan and Guizhou. Within this single province, unmatched in the complexity and scope of its history, landscape and peoples, you'll find a mix of geography, climates and nationalities that elsewhere on Earth take entire continents to express. This diversity makes Yunnan as difficult a place for the modern traveller to come to grips with as it was for successive dynasties to govern, and it's rare to feel that you've done more than obtain the most superficial of impressions.

The northeast of the province is fairly flat and productive, seat of the attractive capital, Kunming , whose mild climate earned Yunnan its name, meaning literally "South of the Clouds". Increasingly touristed, it's nonetheless a charming area, with enjoyable day trips to nearby scenic marvels, and easy access to a varied bag of little-visited sights southeast towards the border with Vietnam , only recently opened up after a decade of war.

West of Kunming, the Yunnan plateau rises to serrated, snowbound peaks extending north to Tibet and surrounding the ancient historic towns of Dali and Lijiang , while farther over is subtropical Dehong , a busy trading region and unlikely Chinese holiday destination on the central border with Burma . Yunnan's deep south comprises a further isolated stretch of this frontier, which reaches down to the tropical forests and paddy fields of Xishuangbanna , a botanic, zoological and ethnic cornucopia abutting Burma and Laos - about as far from Han China as it's possible to be.

Moving amongst this blur of border markets, mountains, jungles, lakes, temples, modern political intrigue and remains of vanished kingdoms are 28 recognized ethnic groups , the greatest number in any single province. Providing a quarter of the population and a prime reason to visit Yunnan in themselves, the indigenous list includes Dai and Bai, Wa, Lahu, Hani, Jingpo, Nu, Naxi and Lisu, plus a host shared with other provinces or adjoining nations. Though much of what you'll initially glean of their cultures is put on for tourists, anyone with even a couple of days to spare in Xishuangbanna or Lijiang can begin to flesh out this image. With more time you can look for shyer, remoter groups leading lives less influenced by the modern world.

Yunnan's scale makes travel very time-consuming, and, whatever your usual preferences, it's tempting to fly occasionally. Fortunately Yunnan Air is one of China's better airlines, and a good excuse to avoid retracing a back-wrenching, four-day bus journey. The state of country buses and roads is often surprisingly good - Yunnan is currently ten years ahead of schedule on its road building projects - and, whatever their condition, it's an undeniable achievement that some routes exist at all. Make sure you travel at least briefly along the famous Burma Road between Kunming and the western border, built with incredible determination during the 1930s. There's a limited rail network inside Yunnan - one service down through the southeast to the Vietnamese border, and a recently completed line to Xiaguan, near Dali - though Kunming is well linked to the rest of the country via Sichuan and Guizhou. The weather is generally moderate throughout the year, though northern Yunnan has cold winters and heavy snow up around the Tibetan border, while the south is always warm, with a torrential summer wet season.

One factor confusing travel in the border regions is the oscillating open status of various areas, although, technically, almost all of the province is accessible to foreigners. The causes for closures vary from dangerous roads to reported outbreaks of plague, but it's often due to the army looking for illegal cross-border traffic in cars, timber, gems and opiates . Most of the world's heroin originates in Burma and is funnelled through China to overseas markets, often with the help of local authorities. Officially, the Yunnanese government is tough on the drug trade, executing traffickers, forcibly rehabilitating addicts and intercepting around twice the quantity of heroin netted by Thai officials in any one year. All this means that, open or not, there are military checkpoints on many rural roads, where you'll have to show passports and can expect to have your luggage rigorously searched, and it is possible that you may be fined and turned around if you wander too far off-track. It pays to be polite, but things are often easier if you avoid appearing fluent in Chinese in these circumstances.