Introduction to Dijiaozi: In February 1934, Yang Jingyu, commander of the First Army of the Northeast People's Revolutionary Army, led his troops to establish a guerrilla base in the Sankuishi area. They dug and built "grounds" on the sunny side of the hillside. "The cellar" can not only sleep people, but also store food and medicine. Nowadays, many of these ruins have been destroyed by landslides, but the harsh fighting conditions at that time can still be seen from their appearance.