关山 are the passes and mountains of the frontier.
李白's poem opens
明月出天山，
苍茫云海间。 'The bright moon rises over the Tian Shan, in a vast sea of clouds.'
陆游's, written in 1177, mourns fifteen years of peace bought from the Jin while the generals sat idle. The Lingnan school painter Guan Shanyue (1912–2000) bears the same name.
