Led Zeppelin didn't release many singles, they didn't believe in them but luckily Immigrant Song is one of them. They hated the music press and wanted to release albums to be listened to as albums not as little slices taken from them.
Immigrant Song was written when they were on tour in Iceland - which is why they 'come from the land of ice and snow'.
There are very few bands that match Led Zeppelin in my opinion. Often they seem to get left out of lists that contain the likes of The Beatles, The Rolling Stones, The Who, Pink Floyd etc.
To Me, this is simply wrong. They are one of the best bands in the world ever. Turn this up loud and tell me I'm wrong!
Led Zeppelin - Immigrant Song