In the greater context of the album, and it’s rumored demonic element, “Agadez” is a sort of dramatic monologue. The speaker being a wicked soul bound in purgatory for untold eons, attempting to influence the physical world by unnatural means.

Seriously, this dude is EVIL.

Agadez is the largest city in central Niger, with a population of 88,569 (2005 census). It lies in the Sahara and is the capital of Aïr. The city still sees the arrival of caravans, bringing salt from Bilma.

The Agadez Grand Mosque (pictured below) is a prominent mosque in Agadez, Niger. Made of clay, it was originally built in 1515 and restored in 1844.
Thanks to wikipedia: https://en.wikipedia.org/wiki/Agadez