These features not only form the natural borders, but also contribute to distinct customs, preferences and traditional diversity. China is bordered by India and Central Asia. Its eastern seaboard is 14,500 km and low lying. The coastline stretches across the boundaries of the South and East China Sea that separates the nation from Japan and Korea. The ancient Chinese civilization flourished along the fertile Yellow River basin. This has been home to its political system and hereditary monarchies. The physical characteristics mainly comprise plateaus and mountains that are lower in the east. The country is enriched by the waters of the Yangtze, Huang He, Amur, Pearl, Mekong, and the Brahmaputra. The alluvial plains along the shores of the East China and Yellow Sea are naturally densely populated. There are grasslands along the borders of the Inner Mongolian plateau that lies to the north and hilly and mountain ranges towards the south. The deltas of the Huang He and Yangtze River dominate the terrain of East-Central China. China largely depends on an agrarian culture and most of the arable lands lie along the rivers. The great alluvial plain in the north and the calcareous tableland in the south provide it with a distinct geographical identity. It cradles Mount Everest, the tallest mountain in the world. To the northwest of China lie high plateaus and desert landscapes. This region is home to the Taklamakan and Gobi Desert. The southwestern border comprises high mountains and the deep Yunnan valleys that form the country's natural borders with Vietnam, Burma, and Laos. Its Paleozoic formations are mostly marine, except those in the upper carboniferous system, while the Mesozoic and Tertiary deposits are more freshwater and estuarine in nature. The Great Plain that lies to the north is characteristic of volcanic cones. The basalt plateaus are the main features of the Liaodong and Shandong Peninsulas. The climatic conditions of the country vary greatly. While the day time temperatures in summer, in the northern zone reaches above 30 degrees Celsius with Arctic-like winters, the central zone enjoys a more temperate and continental climate. In southern China, the climate is subtropical in nature, with very warm summers and mild winters. Springtime witnesses a number of dust storms that are the result of prolonged drought and very primitive agricultural practices. Research reveals that these storms carry dust from the mainland to as far as the west coast of the United States! The country is now facing environmental issues such as water scarcity and soil erosion, as well as high pollution levels.