津关险塞

Explanation: Tianjin: Ferry; off: mark; risk: strategic importance of the land; plug: fortress. Lushan Chuan pass that water, strategically located and difficult place. 　　Source: "Records of Emperor of the century": "Good, good words almost JIA is also pushing, said: 'Qin and princes more than thirty counties in Shandong, Tianjin Calligraphists off, according to insurance plug, repair Jiabing and keep it."