Where does Disgaea 4 place Chronologically

I haven't played Disgaea 2 or 3 yet and the first Disgaea game I played was Disgaea 4. I recently got Disgaea 1 and found out Flone was just an angel and knowing the list of DLC for Disgaea 4 she apparently becomes a "Fallen Angel" sometimes during Disgaea 2 and/or 3, then is Disgaea 4 she's an Arch Angel.

So I'm just wondering where chronologically Disgaea 4 takes place, does it take place after Disgaea 3 or is it a Prequel to Digaea 2 and/or 3?