Civilization

A civilization is a city that has grown beyond its walls and is beginning to build vehicles. At this stage in its development, a society is quite powerful, and is in a position to take over the planet it is on. However, very few civilizations can stand up to a UFO unless it has made an alliance with another, more powerful civilization, probably from another planet. Although they are still civilizations after they have built a UFO, a better name would be an Empire.