Manchuria

“Manchuria” can refer to any one of several regions of various sizes.

1. Northeast China: generally defined as the three provinces of Heilongjiang, Jilin and Liaoning
2. The above, plus part of northeastern Inner Mongolia
3. The above, plus the Jehol region of Hebei province. The part of Manchuria in China is commonly called Inner Manchuria to contrast it with Outer Manchuria (see below)
4. The above, plus Outer Manchuria or Russian Manchuria, a region in Russia that stretches from the Amur and Ussuri rivers to the Stanovoy Mountains and the Sea of Japan. Russian Far East comprises Primorsky Krai, southern Khabarovsk Krai, the Jewish Autonomous Oblast and Amur Oblast. These were part of Manchu China according to the Treaty of Nerchinsk of 1689, but were ceded to Russia by the Treaty of Aigun (1858);
5. The above, plus Sakhalin Oblast, which is generally included on Chinese maps as part of Outer Manchuria, even though it is not explicitly mentioned in the Treaty of Nerchinsk.