The Manchurian Incident in 1931 marked the beginning of the bloody invasion of northeastern China by imperialist Japan. In 1934, Yang Jingyu established the general command of the Northeast Anti-Japanese United Army and repeatedly defeated the enemies with a force inferior in number in NE China's vast and icy forest. The Japanese invaders called him "the most mortal malady" of Manchukuo, the puppet state of the Empire of Japan, and dispatched a large force of 75,000 to hunt down Yang's troop of 300.

In February 1940, Yang was killed in battle. The Japanese dissected his body and found only undigested grass roots and bark left in his stomach as he had eaten nothing for five consecutive days before dying. 

Yang's persistence earned the tribute of his mortal foes, who held a memorial ceremony after his death.