What is "hailongtun"

Hailongtun is a ruined castle in Zunyi, Guizhou province, China. It is on Longyan Mountain, near Baisha Village of Gaoping Town. Hailongtun is an example of a well-preserved medieval castle in China. It is one of the Major National Historical and Cultural Sites of China.

Hailongtun was established in 1257 during the Southern Song Dynasty. It served as the castle of the Bozhou Tusi (native chieftain system) Yang family from the Southern Song to the Ming Dynasty. During year 28 of the Wanli era (1600), the Ming army defeated the rebel Tusi army, with the last chieftain Yang Yinglong committing suicide and the castle was burned down.

The castle occupies a total area of , with 6 eastern and 3 western passes and walls nearly long. It is surrounded by cliffs on all four sides with only one entrance from the mountain road. The pass on the mountain side was known as the Feihu Pass. The one to the east was called Feilong Pass. At the foot of the right hill is a copper column pass, whereas at the base of the left hill is the iron column pass.

The castle's architecture reflects its strategic importance. The city gates were flanked by archer’s towers. Although there is nothing to support the tale, it is said that once a large stone wall, wide enough to allow horses to gallop on it, connected all of the passes. A deep moat surrounded the city.