The most famous line of frontier poetry is 'the moon of Qin, the pass of Han.'
Tips
history
From 《出塞》 by 王昌龄 (Wang Changling, Tang dynasty): '秦时明月汉时关,万里长征人未还。但使龙城飞将在,不教胡马度阴山.' Canonical 边塞诗 (frontier poem). 飞将 = 'Flying General' 李广 Li Guang of the Han — the poem laments that no Li Guang-like hero defends today's borders.
usage
This is an 'interlocking parallel' (互文) — the moon is of both Qin and Han, and so is the pass. Classical rhetorical device: don't read it as two separate ages.