South West China, the exotic area, home to many minority ethnic groups. Like other parts of West China, it is far less prosperous than the eastern and southern coastal regions.
Much of the terrain is quite mountainous. Tibet and Northwestern Yunnan are located on the Tibetan Plateau and have many very high mountains; including the world's highest (Mount Everest) which is located in on the Tibet/Nepalese border. Guizhou and Guangxi have smaller mountains, including the karst limestone terrain, with fantastically gum drop shaped hills, terraced rice fields, and many caves.
The Wikitravel itinerary Overland Kunming to Hong Kong covers travel through this region.