Can you tell me where this poem comes from?

Cai Wenji: What cannot be solved is not this chess game, but the knot in your heart\ In the land of the Hu, I think of my son when I return home~\ This journey is far, take care, my lord!\ Half a lifetime apart, unable to return~\ A sad song can replace tears, looking far can signify homecoming…\ Let me play a tune for you~\ There is painting in the poetry, and people in the painting\ The sky has no end, the earth has no boundary, my heart is troubled, and so it is.\ Death: Wandering in a foreign land with sorrow… heartbroken……\ Ultimate: Sorrow of the Southbound Goose\ Besides one being Cai Yan's 'Eighteen Songs of a Nomad Flute', where do the other lines come from? Today's gaming session was so fun