Manchuria in a 1735 French map.
Manchuria is an area of Asia northeast of China and east of Mongolia. The name was applied to the area by Japanese cartographers in the late eighteenth century and spread to Europe via the Dutch. The area was conquered by the Mongols in the early thirteenth century and remained under Mongol rule until the Mongol emperors were overthrown 150 years later. The rulers of Manchuria remained allied with the Mongols until the Ming dynasty conquered them in the early fifteenth century.
In the late sixteenth century the Jurchen chief Nurhaci began to unify the three main Jurchen tribes. In 1635 Nurhaci's son Abahai renamed the Jurchen the Manchu and began to conquer northern China. Upon Abahai's death in 1643, he was succeeded by his five-year-old son Fulin under a regency established by Abahai's brother Dorgon. As regent, Dorgon continued Abahai's conquests, conquering Peking in 1644 and making the Manchus rulers of China. The Manchu dynasty continues to nominally rule China, although their empire broke up in the 1940s during the Global War, and as of 1971 China is actually ruled by various warlords.
In 1891, Diego Cortez y Catalán, the President of the powerful Mexican corporation Kramer Associates, began to expand his company beyond Mexico by financing a railroad construction project in Manchuria. The company's interests in Manchuria continued to expand after Mexico conquered Siberia from the Russians in 1899. Although Sobel does not specifically say so, it is likely that Manchuria is under the control of K.A.'s Japanese allies in 1971.