On the Kingdom Map you can send troops to occupy a resource tile and gather the resources. You can then use these resources to develop your City.
To gather, select a resource tile and then tap ‘Occupy’. Choose the troops you wish to send and tap “MARCH’. Your troops will return when they have gathered all the resources they can carry.
The amount of resources your troops can carry is dictated by the number and type of troops in the march. The larger your troop load is, the more resources you can bring back.You can also boost the amount gathered through Talent Skills, Dragon Guardian Skills, Research and Gathering Boost items.
The higher the level of resource tile, the more resources on offer. The closer you are to the center of the Kingdom, the higher the level of resource tile.