The origins of the Manchu can be traced back more than 2,000 years to the forest- and mountain-dwelling peoples of northeastern China such as the Sushen tribe, and in later periods to the Yilou, Huji, Mohe, and Nuzhen (Jurchen) mentioned in historical records. Their ancestors established the Bohai State between the seventh and eighth centuries A.D. , and were a part of the Liao Empire (947-1125), which extended over Manchuria, Mongolia, and northeastern China. In 1115, the Jurchen tribes of northern Manchuria became unified, and in alliance with other non-Han agricultural and pastoral peoples of the region established the short-lived Chin (Jin) dynasty, which held control of the northeast and extended southward into inner China as far south as the Huai River. At their main capital, Yanjing (now Beijing), they built a Chinese-type bureaucratic state and recruited Chinese officials to help run the empire. By 1215, under pressure from the advancing Mongols, the capital was moved southward to Kaifeng; the Chin fell in 1234. Four centuries later, they were more successful, establishing the Qing dynasty (1644-1911), which ruled all of China. During the Qing, many important Han writings were translated into Manchu. There was frequent interaction with Han and Mongols, and marriage alliances between Manchu and Mongols. Intermarriages with Han were not permitted until the mid-nineteenth century. During the Qing years, many Manchu, particularly those living in or on the borders with interior China, adopted much of Han culture and assimilated to Han styles of life. Migrations of Han from north China into the northeastern provinces during the twentieth century further hastened assimilation and the adoption of the Chinese language. By the end of the nineteenth century, Russia and Japan were competing for control of China's northeastern provinces, with their rich timber lands, farm lands, and mineral reserves. Japan occupied the area in 1931 and in 1932 proclaimed Manchukuo as an "independent" state under the rule of Pu Yi Aisengoro, the last of the Qing emperors. After World War II, Chinese sovereignty was restored.