After 180 days, one tribe must hold at least 70% of the villages. The world will be open for 180 days before an end game can even start. After 180 days a tribe must hold at least 70% of all villages for the world to enter into end game. It is rare that one tribe can reach 70% by the 180 day mark but it has been done. So basically a tribe must hold 70% dominance (70% of villages) before the world will enter end game.
