Inner Asia refers to landlocked regions within East Asia and North Asia that are part of today's Western China, Mongolia, the Russian Far East and Siberia. It overlaps with some definitions of Central Asia, mostly the historical ones, but certain regions of Inner Asia (such as Northeast China) are not considered a part of Central Asia by any of its definitions. Inner Asia may be considered as the "frontier" of China, and as bounded by East Asia, which consists of China, Japan, and Korea.The extent of Inner Asia was seen differently in different periods. "Inner Asia" is sometimes contrasted to "China Proper", that is, the original provinces, those with majority Han Chinese populations. In 1800 it consisted of four main areas, namely Manchuria (modern Northeast China and Outer Manchuria), Mongolia (Inner and Outer), Xinjiang and Tibet. These areas had been recently conquered by the Qing dynasty but were governed through different administrative structure not as regular provinces during most of the Qing period. The Qing government agency known as the Lifan Yuan was established to supervise the empire's Inner Asian regions.