There are 3 types of areas:

1. Badland -> You will begin the game here.

2. Plains -> You may enter this area after completing the [Banner Raised High] milestone. This area contains Alliance Iron.

3. Fertile Land--> You may enter this region after completing the [Grand Conquest] milestone for higher-level resources.

The system only allows the Alliance HQ to be built on Badland and Plains, but not Fertile Land