出典:Wiktionary
The 21st century sense referring to territories ceded by China to Russia in the 19th century seems to have been popularized[1] with the May 2004 creation of a Wikipedia article for Outer Manchuria; it may be an instance of citogenesis. The same article may also be the source of Inner Manchuria referring to Manchuria (all northeast China).
In 21st century usage in English, the term Outer Manchuria most often refers specifically to territories ceded by the Qing Dynasty (Manchu) to the Russian Empire in 1858 and 1860. This sense is closely associated with discussions of irredentism. However, in 20th century usage, Outer Manchuria or outer Manchuria refers to remote parts of Manchuria or northeast China in a more general sense. Additionally, Outer Manchuria can be used in a figurative sense like Timbuktu to refer to a proverbially remote location.