Answer:
Line 30 in the poem suggests that there was a war that was about to be waged in Xanadu.
Step-by-step explanation:
"Kubla Khan" is one of the most celebrated incomplete poetry in literature. It is written by Samuel Taylor Coleridge. The poem is a fragment of the dream or vision that he saw but could not write the full dream as he remembered only a part.
In line 30, the speaker said that he heard the ancestral voices of war. If the poem would have been written completely, or if the story would have continued there would have been a war waged on Xanadu. The beauty of Xanadu state would have been completely shattered with the war.
Line 30:
"Ancestral voices prophesying war!"