"Yang Gong banned Japan", also known as "Thirteen Bannings in Yang Gong", was handed down by Yang Junsong, a geomantic master in the Tang Dynasty.
These thirteen "taboo days" are 1 month 13, February 1 day, March 9, April 7, May 5, June 3, July1day, July 29, and July 29.
Yang Gong's main works: According to the instructions of The Son of Man, he wrote nine books: The Book of Doubting the Dragon, The Book of Shaking the Dragon, The Picture Clip, The Method of Four Points, Li Zui Fu, Painting the Sand, The Book of Fetal Abdomen, The Book of Looking at the Dragon, and The Method of Inverting the Staff. According to Shu Shu Shu Series (IX), Yang Gong wrote five books: Yi Long Jing, Han Long Jing, Burying with an Inverted Staff, Qing Nan Ao Yu and Tian Yu Jing.
There are many records about Yang Gong's geomantic theory works in other geomantic books. According to textual research, there are at least three of Yang Junsong's most reliable works: Qingnangao Yu, Tianyu Jing and Yuchi Jing.