There are three types of building resources in the game: Lumber, Iron and Stone. They are used to build and upgrade structures in your city. They are also used to build clan defenses and processing structures and are later converted by them into clan resources.

Build and upgrade Lumberjacks’ houses, Foundries and Stonecutters’ houses in order to increase resource production. You can also harvest resources on the Kingdom map or get resources out of clan gift chests or the ones that are bought in game’s offer shop. Finally, players can exchange resources with each other with the help of Caravan. You can read more about this and other buildings here.