well learn to post an opinion before you post an opinion.
quote from wikipedia:
The term civilization (British English also civilisation) has a variety of meanings related to human society. Most often it is used to refer to "complex" societies: those that practice intensive agriculture; have a significant division of labour; and have population densities sufficient to form cities. "Civilization" may be used more broadly to refer to the sum, or current extent, of human accomplishment and spread (human civilization or global civilization).
Human civilization is a civilization. Let's say there were some alien civilization living on a planet that is as complex as us, called "boot" the "boot" would be a civilization.
Your term Civilization is an ancient peoples who built cities. such as the Egyptian civilization. There a civilization to. But then why in Civ 4 is England called a "civilization" when they weren't ancient? because they had what at there time would be civilized life and cities and agriculture etc.
The Celts, Vikings, Zulu, Native Americans, Mali were never "empires" and there in the game. Empire basically (god i'm gonna get flamed at real hard) A Country, State or Nation who has counquered an area and has some sort of government. and tons of other things that i can't think of.
To be in Civ you don't have to be an empire, state, or country to be in. All you need is to be a nation that had some sort of significence in the world.
And Poland did save alot of Europe from becoming Muslim, or falling into the rule of the Ottoman empire. The Siege of Vienna was saved by King Jan III Sobieski who brought a relief army of Poles, Germans, Lithuanians and Austrians to save Austria from becoming an Ottoman State.
Your Opinion is only welcomed in a positive way. and please don't post things you don't know about.