China is located at the east coast of the largest continent (Eurasia) as well as the western margin of the largest ocean (Pacific). It has a land area of about 9.6 million square km, occupying 6.5 percent of the total land area of the world. From the confluence of the Heilong River and its tributary, the Wusuli River, westward to the Pamir Plateau, the distance is more than 5200 km. From midstream of the Heilong River north of Mohe, southward to Zengmu Shoal of the Nansha Islands near the equator, the distance is more than 5500 km. Its population of more than 1.3 billion accounts for approximately one-fifth of the world population.