The New Qing History is a revisionist historiographical trend starting in the mid-1990s emphasizing the Manchu nature of the dynasty. Earlier historians had emphasized the power of Han Chinese to "sinicize" their conquerors, that is, to assimilate and make them Chinese in their thought and institutions. In the 1980s and early 1990s, American scholars began to learn Manchu and took advantage of newly opened Chinese- and Manchu-language documents in the archives. This research found that the Manchu rulers manipulated their subjects and from the 1630s through at least the 18th century, emperors developed a sense of Manchu identity and used Central Asian models of rule as much as they did Confucian ones. According to the new school the Manchu ruling class regarded "China" as only a part, although a very important part, of a much wider empire that extended into the Inner Asian territories of Mongolia, Tibet, the Manchuria and Xinjiang.