This decade could be really messy. Already countries like Iraq, Syria, and the Ukraine are making headlines as forces within the country struggle for independence or control. Given the stage of development so many countries are at right now, we will likely see quite a number of civil wars in the next 20 years or so.
Iraq became a country because some British administrator drew a line around the region. Iraq now includes two or three very distinct groups that don't think of themselves as one nation but instead as three. It seems obvious to say but it's tough to create a nation-state when more than one nation - more than one people - wants to be represented. The Kurds in the north of Iraq have very different values and interests - perhaps irreconciliable differences - from the Sunnis and Shiites in the south.
Before the English and French invented the modern nation-state, the West was mostly defined by city-states, empires, and tribes. A state refers to a form of government. A nation refers to a people who define themselves through some blend of common language, beliefs, culture, history, potential, etc. One nation might include many states. (Think of Italy before 1861, made up of city-states like Milan, Florence, and Venice.) One state might include many nations. (Think of the Holy Roman that at one time or another included Germans, Dutch, Italians, French and Poles.) A nation-state by definition aligns a nation and a state.
As it now stands, it seems difficult to create a modern democracy without first creating a nation-state.
The Ukraine seems to be comprised of two nations right now. The west faces Western Europe, is liberal, better educated and intent on economic and social freedoms. The east faces Russia, is conservative, less educated and speaks Russian. While it is possible to align these two groups, it is very difficult. And the more that the people define their own policies -as happens in a representative government - the more glaring will be these differences, the harder it will be to reconcile. A strong-man leader makes these differences less important simply because these differences have little chance to be expressed; but as information technology, media, and economic power shifts from the center of a country to its people, such differences become more obvious. It seems as though one of the first things revealed in the transition towards a democracy is that these countries are rarely nation-states; instead, they are petty empires of multiple nations that have been ruled over by a strong central government.
Because of this, civil war almost seems like an inevitable step towards the creation of a nation-state. (It happened in the US when the economy and politics developed to the point that states became less defining of the continent than the country, when united States gave way to The United States.) Because of this, it's hard to imagine that the number of civil wars will drop any time soon. This is going to be painful.
P.S. Here's a piece that not only adds a different perspective on the Ukrainian crisis from what you might get in most Western media but seems to buttress the notion that a fundamental problem is that there is no organic whole that encompasses the Ukraine, a country that was pieced together by outsiders after WWII.
Jack Matlock, Ukraine: the Price of Internal Division