The author in their work considers the documents of the State Archive of the Russian Federation unknown to the scientific community from the “Collection of Manuscripts of the Tsarskoye Selo Palace” (fund 583) dating back to the early 20th century. These documents include letters and reports, which, in a varying degree, address various aspects related to the history of Manchuria and which are practically not reflected in the publications on the history of Northern and Northeastern China. The author’s chief concern is the creation of the institution of the “General Commissariat” of the Russian Empire in Manchuria which dates back to the beginning of the 20th century. An attempt to create a similar structure for managing civil affairs was made in 1898 on the territory of the Liaodong Peninsula, but it was not put into practice. The Russian government returned to the idea at the beginning of the 20th century, when a proposal was made to introduce unity of command in the management of the region in order to consolidate the three Military Commissariats (Jilin, Mukden and Heilongjiang provinces) that had been operating independently. The authors of the project of the “General Commissariat” in Manchuria at the beginning of the 20th century, as well as the related documents are not known. The project outlined the idea in detail and provided a financial assessment, but this project was never implemented either. The reason the project was not implemented is probably the change of the situation in the Far East as a result of the Russo-Japanese War of 1904-1905. Referring to this historical source is important for reconstructing a more complete history of Northern and Northeastern China during the early 20th century.