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 and can also be used to construct Clan defenses and processing structures. The latter allow building resources to be converted into Clan resources.

Build and upgrade Lumberjacks' Houses, Foundries, and Stonecutters' Houses in order to increase the production of Clan resources. You can also gather resources on the Kingdom Map or obtain them from Clan gift chests or chests that can be purchased in the game's shop. Finally, players can exchange resources with one another using Caravans. You can read more about these and other buildings here.