How do I unlock additional territories?

As you play through the game new territories will become available for the in-game purchase. You need to meet one or more of the following requirements in order to open each territory:
- gain certain game level;
- complete certain questchain;
- save certain amount of coins or crystals.
So if a territory is not available yet, don't panic, you just need to keep playing for now.
If territory is available for purchase a special icon with wooden arrows appears over it. Tapping it will tell you the requirements. Upon fulfilling the requirements territory is yours to build on as you please.