TNG introduced various civilisations that drive much of the plot in DS9. Season 1: Ferengi Season 4: Trill, Cardassians Season 5: Bajorans Also, Chief O'Bri

TNG introduced various civilisations that drive much of the plot in DS9. Season 1: Ferengi Season 4: Trill, Cardassians Season 5: Bajorans Also, Chief O'Brien and his wife Keiko who were recurring minor characters in TNG have more important roles in DS9.