In many respects this is based upon the successive real world invasions of Europe by mobile eastern groups from the steppe land, such as the Huns and Alans.
Dark Horse Comics | Dark Shadows | Orchestral Manoeuvres in the Dark | The Dark Knight Rises | Dark Avengers | The Dark Side of the Moon | Poker After Dark | Transformers: Dark of the Moon | Committee on Public Lands | Dark Victory | Dark Funeral | dark energy | The Old Dark House | The Dark Tower (series) | The Dark Tower | My Beautiful Dark Twisted Fantasy | Dark Star Orchestra | Thor: The Dark World | Star Wars: Dark Forces | Perfect Dark Zero | Lands' End | Greek Dark Ages | Elvira, Mistress of the Dark | Dominion Lands Act | Dark Knight Court | Dancer in the Dark | Damon Dark | Alone in the Dark | Under Siege 2: Dark Territory | The Dark Avenger |