Salambic

Salambic is the old court language of the Shekemite Caliphate. It is spoken throughout Phar-Shekem and most of the southern empire's official documents are written in this tongue. There is a great deal of scholarship, poetry, and imaginative fiction published in Salambic. Legend holds that Salambic is descended from the language of the Djinn and other elemental spirits, and there is a special sub-branch of evocation magic which uses Salambic for it's incantations.
Arcane casters with proficiency in Arcana may be able to understand a bit of Salambic even if they can't speak it.