The Book of Houma League was discovered by the Shanxi Provincial Cultural Relics Working Committee during the excavation of the Jincheng site of Houma in Shanxi on 1965, and the excavation time was from 10 in the same year to May of the following year. Hou Ma's Letter of Alliance was an agreement signed by Zhao Yang, Secretary of State of Jin State, and Dr. Qing during the 15th to 23rd years of the late Spring and Autumn Period (497-489 BC).
At that time, in order to consolidate internal unity and combat hostile forces, governors and Qing doctors often held such vows. The book of alliance is made in duplicate, one of which is hidden in the government of alliance, and the other is buried underground or submerged in the river to win the trust of ghosts and gods. Hou Ma's letter of alliance was written on a piece of jade with a brush. The handwriting is generally vermilion, and a few are black. The font is close to the bronze inscriptions in the late Spring and Autumn Period.
The "Oath Site" is located in the southeast of Houma Jincheng Site, covering an area of about 3,800 square meters. It is divided into two parts: the book burial area and the sacrificial burial area. There are more than 400 pits (pits for burying sacrifices) found at the swearing-in site, and the sacrifices are generally buried at the bottom of the pits. Cattle, horses and sheep are buried in the pit, and sheep or group books are buried in the pit.
There is also a small niche at the bottom of the northern wall of most ridges, in which a jade offering called "coin" is placed, and several pieces are buried in some pits. These jade coins and sacrifices are sacrifices offered to gods or ancestors when sworn in.
Jade coins used as sacrifices are exquisitely carved. Most of the jade pieces used to write the League Book are in the shape of Gui, the largest is 32 cm long and nearly 4 cm wide, and the smallest is 18 cm long and less than 2 cm wide. These cultural relics add fresh materials to the study of the history of China in the pre-Qin period at the turn of the Spring and Autumn Period and the Warring States Period, especially the history of the late Jin State.
Its discovery is of great significance to the study of China's ancient oath system, ancient Chinese characters, calligraphy art, calendar, sociology, customs and habits, and the history of the State of Jin.