What is the significance of the title of the poem ''Kubla Khan''?

The title of the poem, the alliterative name of a Chinese ruler, immediately establishes a connection with the Orient. As Edward Said argued in his book Orientalism, in the eyes of the western world, the Orient was not a real place but  a mental construct that lumped dozens of disparate and geographically widespread cultures under one name and characterized them in opposition to the West. If the West was supposed to be the place of rationality, masculinity, concreteness, adulthood and practicality, the "Orient" was the land of enchantment, exoticism and dreams. 

Coleridge, an opium addict, insisted his poem arose from a dream. The poem reflects a Westerner's fantasy of the "Orient" as sensuous dreamscape: it is not about the ruler Kubla Khan, per se, but about the imagined landscape he inhabits: his pleasure dome, the scent of his "incense-bearing tree," "A Savage place!" both "holy and enchanted," inhabited by a "damsel with a dulcimer," where a waterfall crashes into the sea, a place both alluring and dangerous ("Beware"). The title thus signals the move from the rational world of the West into the dreamscape of the Other.