2000 years before DS9: The Dominion is founded.
50 years before DS9: Bajor occupied by Cardassians.
Season 1: Bajor is considering application to the Federation. Cardassia, the Federation, Bajor, and the Ferengi Alliance are at peace.
Season 3: The Cardassian government is overthrown.
Season 4: War between the Klingon Empire and the Cardassian Empire erupts