"In the 20th century, why should some people live in such poor conditions? They left their comfortable homes, dived deep into the mountains, and lived in shabby underground houses, enduring every hardship. All they wanted was to drive out the Japanese invaders from their homeland," he adds.

Aside from continued archaeological efforts to uncover more facts, stories of the Northeast United Resistance Army have been told in museums.

The Northeast United Resistance Army historical exhibition hall in Benxi, Liaoning province, showcases a saber once used by Yang Jingyu, one of the founders of the forces who arrived in 1934 and established base areas.

According to Zhou Hao, director of the exhibition hall's research department, the 1.03-meter saber was specially made for Yang, who was 1.93 meters tall. When Yang organized guerrilla fighting in Benxi, he was saved by villager Jiang Guo'en, and they became friends. In 1938, before leaving for Jilin, Yang gave his saber to Jiang as a gift. Two years later, Yang sacrificed his life in Jilin.

Soon after Yang's army left, Japanese troops rushed to Jiang's family to get revenge. Jiang heard of the plan and hurriedly led his family members to hide in the mountains, putting the saber on the beam of his house.