Boat City

Boat City is basically just a large collection of boats with people living in them. Their only resource is fish, and the only city they can approach to trade with (other than Dockopolis, which attacks them when they approach) is Lacostrin. Hence, Boat City trades fish for explosives in Lacostrin and uses the explosives to raid Dockopolis for the supplies they need to live. Dockopolis is incapable of counterstrikes, since they have no boats, and all attempts to build boats are abandoned when the shipbuilder realizes how much it will cost to dock it.