Siwa Oasis is a sacred oasis in Egypt where the group takes refuge and recovers after the defeat in Alexandria and the battle of Kosovo.
It contains an oracle called Al-Ziwa. It is the setting of the invocation of Baraquiel and of the negotiation with the Horseman of War. It appears in Uchronic Paris (recovery, invocation, negotiation).
Historically, the Siwa Oasis was the seat of the Oracle of Amun, consulted by Alexander the Great.