一夫当关

Explanation: Describe the terrain is very advantageous, easily defensible. 　　Source: "History of Ming Biography of a North Korean foreign" about Ukraine Chungju, bamboo two Ling, gut around the song, a 'man guards the pass' of the risk. " Thesaurus:  bolus Scove barrier, One man can hold this pass to guard against ten thousand enemies., Wanfumocui