Readers need remarkably little backstory. Just tell this story, make it good, and they'll love you for it.
I discovered something about human kind a few years back that made my opening chapters much better than they had been. I don't know this is an original thought, but it developed in my brain and helped me.
Life is nothing but people coming in in the middle of the scene. They never get the back story unless it is so important that they are willing to stick out like a sore thumb and ask about it. Only the most necessary information need be given. The story itself will reveal the rest.
People will not listen to my old, boring stories that simply dump information on them. If they don't need to know that stuff for the discussion at hand, why bother?
Stupid stuff. But it helped me.