"South Sudan's crisis began just two weeks ago, on Dec. 15, and it already has observers warning that it could lead to civil war. Fighting has killed an estimated 1,000 people and sent 121,600 fleeing from their homes. International peacekeepers are preparing for the worst; some have been killed and a number of them, including four U.S. troops, have been injured. What's happening in South Sudan is complicated and can be difficult to follow; understanding how it got to be this way can be even tougher. Here, then, are the most basic answers to your most basic questions. First, a disclaimer: This is not an exhaustive or definitive account of South Sudan and its history -- just some background, written so that anyone can understand it."