China, officially the People's Republic of China (PRC), is a sovereign state in East Asia. With a population of over 1.381 billion, it is the world's most populous state. The state is governed by the Communist Party of China based in the capital of Beijing. It exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities (Beijing, Tianjin, Shanghai, and Chongqing), two mostly self-governing special administrative regions (Hong Kong and Macau), and claims sovereignty over Taiwan. The country's major urban areas include Shanghai, Guangzhou, Beijing, Chongqing, Shenzhen, Tianjin and Hong Kong. China is a great power and a major regional power within Asia, and has been characterized as a potential superpower. Covering approximately 9.6 million square kilometers, China is the world's second largest state by land area, and either the third or fourth-largest by total area, depending on the method of measurement. China's landscape is vast and diverse, ranging from forest steppes and the Gobi and Taklamakan Deserts in the arid north to subtropical forests in the wetter south. The Himalaya, Karakoram, Pamir and Tian Shan mountain ranges separate China from much of South and Central Asia. The Yangtze and Yellow Rivers, the third and sixth longest in the world, respectively, run from the Tibetan Plateau to the densely populated eastern seaboard. China's coastline along the Pacific Ocean is 14,500 kilometers (9,000 mi) long, and is bounded by the Bohai, Yellow, East China, and South China seas. China is one of the cradles of civilization, with its known history beginning with an ancient civilization – one of the world's earliest – that flourished in the fertile basin of the Yellow River in the North China Plain. For millennia, China's political system was based on hereditary monarchies known as dynasties. Since 221 BC, when the Qin Dynasty first conquered several states to form a Chinese empire, the state has expanded, fractured and reformed numerous times. The Republic of China (ROC) replaced the last dynasty in 1912, and ruled the Chinese mainland until 1949, when it was defeated by the Communist Party of China in the Chinese Civil War. The Communist Party established the People's Republic of China in Beijing on 1 October 1949, while the ROC government relocated to Taiwan with its present de facto temporary capital in Taipei. Both the ROC and PRC continue to claim to be the legitimate government of all China. China had the largest economy in the world for much of the last 500 years, during which it has seen cycles of prosperity and decline. Since the introduction of economic reforms in 1978, China has become one of the world's fastest-growing major economies. As of 2014, it is the world's second-largest economy by nominal GDP and largest by purchasing power parity (PPP). China is also the world's largest exporter and second-largest importer of goods. China is a recognized nuclear weapons state and has the world's largest standing army and second-largest defense budget. The PRC is a member of the United Nations, as it replaced the ROC as a permanent member of the U.N. Security Council in 1971. China is also a member of numerous formal and informal multilateral organizations, including the WTO, APEC, BRICS, the Shanghai Cooperation Organization (SCO), the BCIM and the G-20.