Yakhch
A unique region, in the sense that it is the only allod that has changed significantly within our observable time. It is known that it was once a typical desert allod, but later a Great Tree was planted there.
It transformed the desert -- drawing out excess salt, anchoring the sands, and raising the groundwater level. Mixed forests began to grow upon the allod, and a different fauna appeared. Now it is more akin to a typical allod of the temperate zone than a hot desert of the south.