China covers an area of about 10 million km2, being surpassed in size only by Russia and Canada. It supports a population of about 1.3 billion people, amounting to one-fifth of the World’s total. They are made up of several different tribal and ethnic groups, speaking different languages. Accordingly, it is a land of great diversity. Highlands, flanking the Himalayas in the west and rising to an altitude of as much as 4,000 m, give way to dissected mountainous county, which in turn passes into the borderlands of the South China Sea. Its mountainous character helps explain the diversity of its people and the fact that it remained isolated from the rest of the World for much of its history.