The center district (600,600) of a battlefield is the stage for Core Base Competition.
 
Brick Belt

The Core Base is surrounded by the vast Brick Belt, where troops marching is extremely hard and marching speed is largely reduced. Camp is not allowed on Brick Belt. A Command Center on the Brick Belt will lose lots of Defense when defeated.

Core Base and Bunker
The Core Base and the Bunker can only be occupied during the event.

Rules of Core Base Competition

For details, please see Event > Core Base Competition