Anyone seen a Slavic Empire?

I've been playing the vanilla version of BI for a few years now and I have never seen a Slavic empire emerge. I'm wondering if others have had the same experience, because in many of my games by the year 410 lots of factions are weakened/worn down and you'd think the Slavs could establish a 3+ province kingdom. In fact, in my last three games (a WRE, Burgundian, and Vandal), the Slavs either ended up dead, ineffective, or ruling Tribus Iazyges.

Of course the issue might not be with the Slavs but just a more general problem with the horde AI. In my current Vandal game the Goths self-destructed before the epic walls of Rome and the Franks, Huns, and Roxolani have pounded themselves into insignificance in Gaul.