The empire is what the player controls throughout their time in the game. Currently a player may control only 1 empire.
An empire is composed of multiple nations. A player starts the game with 3 nations and through gameplay, can acquire more nations to increase the size and power of their empire.
An empire has a level that the player can increase by completing quests to earn experience points. The level of the empire determines the maximum number of nations that an empire may hold and the maximum level of town centers.
Normally an empire may control a number of nations equal to ten multiplied by the empire level. A nation that is conquered beyond this limit will not be gained by the empire.