Large drainage facilities discovered in ancient C. China fortress
A large-scale drainage system was discovered in the Yongshun old Tusi fortress in Central China's Hunan Province, shedding light on why the 800-year-old rampart is still standing today.
Located in Yongshun County in the Tujia-Miao Autonomous Prefecture of Xiangxi, the fortress was first built in the year 1135 A.D. Lying at the bank of a river, it is considered the largest, oldest and best preserved Tusi fortress in China.
The Tusi system was an ancient chieftain system adopted by feudal Chinese emperors to govern ethnic minorities in the southwest from the 13th to the early 20th century. "Tusi" refers to a tribal leader appointed as an imperial official by the central government.
http://www.china.org.cn/arts/2017-12/11/content_50097046.htm
