The analogy was further strengthened by 饱经沧桑 bǎojīng-cāngsāng which means having experienced many vicissitudes of life. As if this was not good enough, it is further enriched by 桑榆暮景 sāngyú-mùjǐng which means the closing years of one's life. 桑榆 sāngyú by itself means sunset or old age while 暮景 mùjǐng means scene at dusk or situation at old age.
It is amazing how much a simple word like 桑 sāng can convey. It is as if the whole content of the poem can be condensed into that single word making one wonder whether the poet used the word to create the poem…