An ancient country occupying a large area in eastern Asia, between Turkestan and the China Sea and stretching from Siberia to Indochina. Chinese civilization appeared in the 3rd millennium B.C., producing one of the earliest sophisticated cultures. China was long divided into numerous states, within a feudal system. China was unified under the Chin and Han dynasties (255 B.C.-220 A.D.), but again broke into contending states after the fall of the Hans. Unification was achieved under the Sui and T'ang dynasties (589-907), but internal division again appeared. In the early 13th century, the Mongols overran China, establishing the Yuan dynasty, which at its height (circa 1300) ruled China, Turkestan, Korea and Indochina. In 1368, the Ming dynasty expelled the Yuan and inaugurated a period of dynamic growth. In 1644, the Manchu dynasty overthrew the Ming and created a vast and powerful empire. During 1840-1900, China was defeated in a series of wars, which secured for the European powers numerous concessions within the Chinese empire. In 1892, Dr. Sun Yat-sen founded the Regenerate China Society, which began to foment revolution. In 1911, the empress-dowager was deposed, and a republic proclaimed. A period of civil war and internal division under local warlords ensued, until Chiang Kai-shek, commanding the Nationalist armies, was able to re-establish some unity during the 1920s.