Connection to the Oriental theme that runs throughout the poem. Coleridge never visited Africa or the Orient, but this poem contains many Oriental themes. This just shows how much of an influence the Orient had on English authors. This idea was also proposed by Edward Said in his book Orientalism.
Alph
Connects to the myth about this river sinking into the ground and emerging as the fountain Arethusa, which connects to the fountain mentioned in the second stanza of the poem. However, since one of the themes of the poem is creation, Alph could also be a link to Alpha, which is defined as the beginning of all things.
Mount Abora
In the first draft of the poem that Coleridge wrote, Mount Abora was actually written as Mount Amahra, which is where the connection to Milton comes in.
Rills
Connects nicely to the Alph River, which flows through Kubla Khan's lands in the second stanza. This river, in turn, connects to the serpent that slithered through the Garden of Eden in the Old Testament. Both the river and the serpent destroy a beautiful garden from within. The rills and river are also a connection to Coleridge's poem "The Brook," which never really satisfied Coleridge. The image of the river and the rills in "Kubla Khan" were more to Coleridge's liking.
Xanadu
Also the topic of John L. Lowes's book The Road to Xanadu.