That's the old empire Cale. I could be wrong. But I think it underwent reformation during those eras. This is, at least 400 years ahead of the events that took place in Morowind. Maybe even more but I'm unsure, however as I said there's nothing stopping you from using the rank.
And Dragonsbane is just the group that everyone here is apart of. (Except a few) Basically filling in the dragonborns boots.
Their aim essentially the same. To kill Alduin and end the dragon threat.
It requires little knowledge from the actual game.