In order to create a Civilization, you must determine:
- It's borders
A good way to determine the borders would be to see where the people that make up the country historically lived. If your country was made up primarily of the Bantu people of Africa, it'd be important to look at maps of where the Bantu historically lived for a rough idea of the country's area. Once you've determined the rough area, look up maps of rivers around the area and base the borders on them, borders are usually divided by rivers. Though occasionally, unique landmarks such as the great wall could divide two countries.
- It's government system
See the Government page for more detail. The most common governments today are Capitalist Democracies and one-party communist states, with a few constitutional monarchies left over; But in a universe where ancient Israel conquered the whole middle-east, rule by judges would probably be more common.
- It's history
It's important to make a feasible and realistic history, and you should usually create the nation based around the history and not vice-versa. For Example, if the Russians died off in the black plague, the Russians would never have conquered the native Siberians, and the Sibir Khanate would be the only remaining power in northern Asia.
- It's flag
This one may not always be applicable (nations in Atra Mors use military banners), but flags will usually be an important part of your country, and should be based on symbolism important to the people of the country; A Christian country might have a cross on it's flag, for example.