That is not a truly sane question to ask about people such as the Mongols. When the Mongols did what they did they were simply doing what they wanted to do. The idea of "hero" or "villain" is simply out of the picture.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.