Shing Mun (Chinese: 城門) is an area between Tsuen Wan and Sha Tin in the New Territories of Hong Kong. It used to be, as suggested by its Chinese characters, a gate between the two areas separated by a range of hills. The Shing Mun Valley carries water to Shing Mun River. Before the construction of Shing Mun Reservoir, there were several villages near the valley. Some of these villages were later relocated near the Tsuen Wan entrance of Shing Mun Tunnel.
Map of Upper Shing Mun Reservoir, Lo Wai, Hong Kong
The area played a major role in the defense against Japanese Invasion of Hong Kong. Gin Drinkers Line is across the area.
Because there were many major constructions and geography features in the area, Shing Mun may mean one of the following by context:
References
Shing Mun Wikipedia(Text) CC BY-SA