Ogalala and Cheyenne River Sioux Indians
There's no perfect answer to this question (even the question acknowledges this problem). In my opinion, the U.S. was put on a path to Civil War the very moment the U.S. Constitution was signed. The Constitution brought a bunch of colonies into a union together, even though some of those colonies relied heavily on slavery and believed that slavery was morally defensible, while others did not rely on slavery and believed that slavery was a terrible thing. It was only a matter of time before the debate over slavery turned into a violent clash over slavery.
The answer
Initiative,referendum,recall.
Well, you have to think about how this could have happened. A lot of cities and countries have all been hit by some sort of disease or natural disaster but do they both have them. I would say false, you have to understand that not only do they go under that they also suffer from economy losses and from political misunderstandings and troubles. So no, those would not be the only two common factors.