Relics of the Crusades is an expansion published in Fanatic Online magazine, issues #96 & #97. It is set in Araby during the Crusades. The campaign itself is very detailed and can be considered semi-official. You can find part one and two of the campaign rules below (also available on the downloads page under Fanatic publications).
Relics Of The Crusades Pt. 1 : Campaign rules, locations, scenarios, rules and characters.
Relics Of The Crusades Pt. 2 : Warbands, Arabian tribes, Clan Skryre, Slavers, the Fallen, Hired Swords and Dramatis Personae.