China, a country of continental dimensions 2,500 miles from the Pamir Mountains in the west to the Pacific Ocean and 2,000 miles from the Amur River in the north to the Indochinese border in the south. At 3.7 square miles, it is slightly larger than the 3.6 million square miles of the United States. The area varies in topography, climate and vegetation ranging from subarctic taiga (evergreen forests) in the northeast to tropical jungles in the southwest, steppes and deserts of Chinese Turkestan in the northwest to high plateau of Tibet in the west and the temperate river valleys in the east. Deserts and high mountains separate China from other civilizations of Asia. The difficulties and dangers associated with such travel tended to isolate China. Conversely, great river valleys and coastal plains make internal communications easy and have helped unify the Chinese. China can be divided into two broad parts, north and south. Yellow River dominates North China. It brings water and deposits the layers of silt and has brought cruel floods that have given it the name “China’s sorrow”. The Huang He, or “Yellow River”, begins in the highlands of Tibet. It flows for more than 3,000 miles until it empties into the Yellow Sea. It is the second-longest river in China. The Huang He is the muddiest river in the world. It is called the “Yellow” River because of the loess or yellow-brown soil that its waters carry along. When the Huang He floods it deposits loess on the surrounding plain. The Huang He has carpeted the North China Plain with a thick layer of soil. This makes the land perfect for growing crops, especially a grain called millet. The Chinese people also call the Huang He “China’s Sorrow”. The river was unpredictable and sometimes dangerous. Destructive floods could come without warning. Sometimes a flood drowned thousands of people. At times, the river flooded with such force that the water cut an entirely new path. To help control the flooding, early Chinese people built dikes along the banks of the Huang He. A dike is a protective wall that holds back the waters. These dikes only worked for a while. As river water flowed along, some of the loess settled to the bottom. This raised the level of the river. The river rose high enough to burst through the dikes. Hot in summer and cold in winter the North China plains receive little rainfall. Barley and millet are the main crops and donkey and oxen are the chief draft animals. The Tsingling Mountains separate the drainage basins of the Yellow and Yangtze Rivers. The Yangtze valley and the Xi (West, also called Pearl) River valley constitute South China. A coastal plain extends along the entire coastline. Southern China receives abundant rainfall and has mild winters and hot summers. It is the land of double and triple crops each year, paddy rice and water buffalo and canals and lakes. Monsoons from the South China Sea bring rains to the southern half of China. Geographic barriers such as mountains and seas cut China off from other lands. In fact, the Chinese did not call their land “China”. They were so sure that they lived at the center of the world that they called themselves the “Middle Kingdom”. Civilization began in China along the Huang He and later spread to the wetter south along the Yangzi River, the longest river in China. The rivers brought fresh, fertile topsoil to the land. Because of this, China’s first farming villages developed along its rivers.