If I remember correctly...
It was originally called "Driving To Kashmir," and Page was inspired by a lengthy drive from Goulimine to Tantan, which is a deserted road in the Moroccan Sahara. He drove it fairly frequntly and he always thought that the drive would never end, which inspired the song's length. The music itself was inspired by the fact that there was no scenery on the road, except for the occaisonal camel and rider.
Does that help? :guitar: