Final answer:
The poem "Kubla Khan" was written by Samuel Taylor Coleridge, allegedly as he awoke from an opium-induced dream but was interrupted, resulting in the poem's incomplete state.
Step-by-step explanation:
According to legend, the poem "Kubla Khan" was written by Samuel Taylor Coleridge after he experienced an opium-influenced dream. Coleridge claimed that he had a profound and vivid dream after reading about the Khan’s palace from Samuel Purchas’s travel book, "Purchas His Pilgrimes." Upon awakening, he started writing the lines of the poem but was interrupted by a 'person from Porlock', which made him unable to remember the rest of the dream, leaving the poem famously incomplete. This accounts for the vivid and dream-like imagery present throughout the poem that has captivated readers ever since.