That is supposed to be the Master of the Oasis badge and you earn it by completing all the quests in Krokotopia. As far as I know (never did get a response) it is a glitched badge. It does not show up in your book even though you have done everything including the Tomb of the Beguiler.
Admins any help on this badge? The subject has been mentioned in several topics on the forums for the last few months now and still haven't heard about why it is not fixed or whether it is a known bug.
I have completed all the quest that could find in krokotopia and earned all the badges stating that each area is complete. However, I still have not received my master of the oasis badge. I would greatly appreciate it if you could look into this and let me know what I can do to get my badge.