The Manchurian plague was a pneumonic plague that occurred mainly in Manchuria in 1910–1911. It killed 60,000 people, stimulating a multinational medical response and the wearing of the first personal protective equipment (PPE).

Manchuria is a term that refers to a region in Northeast Asia encompassing the entirety of present-day Northeast China, and historically parts of the modern-day Russian Far East, often referred to as Outer Manchuria. Its definition may refer to varying geographical extents as follows: the Chinese provinces of Heilongjiang, Jilin, and Liaoning but broadly also including the eastern Inner Mongolian prefectures of Hulunbuir, Hinggan, Tongliao, and Chifeng, collectively known as Northeast China; the aforementioned regions plus the homelands of ancient Jurchen and their descendant Manchus, parts of these region were ceded to the Russian Empire by the Manchu-led Qing dynasty during the Amur Annexation of 1858–1860, which include present-day Amur Oblast, Primorsky Krai, the Jewish Autonomous Oblast, the southern part of Khabarovsk Krai, and the eastern edge of Zabaykalsky Krai, collectively known as the Outer Manchuria or Russian Manchuria.