Why occupy territories?

Too many!! Now I can not occupy more?? What to do??

Occupying territories is part of the Doomsday Conquest event. Occupying the tainted resource tiles will let you gather resources. You need to build the honor structure buildings around Alliance centers though to give yourself immunity to infection and process the resources to allow you to improve and then occupy higher level plots.

The event is optional so you don't need to take part. It can gain your some resources though if you do.