 The Manchu Qing referred to the Han Chinese inhabited 18 provinces as "nèidì shíbā shěng" (), which meant the "interior region eighteen provinces", or abbreviated it as "nèidì" (), "interior region" and also as "jùnxiàn" (), while they referred to the non-Han areas of China such as the Northeast, Outer Mongolia, Inner Mongolia, Xinjiang, and Tibet as "wàifān" () which means "outer feudatories" or "outer vassals", or as "fānbù" (, "feudatory region").These waifan were fully subjected to and governed by the Qing government and were considered part of the China (Zhongguo), unlike wàiguó (, "outer/foreign countries") like Korea, Vietnam, and the Ryukyus, who paid tribute to the Qing but were not part of China.In the early 20th century, series of Sino-Japanese conflict had raised Chinese people's concern for national unity, and the concept of a unified, undivided Chinese nation became more popular among Chinese scholars.