Same game as the Halychnians above. The Grand Principality of Halychyna did well and subjugated all of Khazaria, moved the capital to Kerch in Crimea, and changed the empire to the Tsardom of Great Halychyna. Does well for a while, then a couple generations later, the Tsar's heir gets caught in an incestuous relationship with his aunt, and since he only has daughters of his own, gets disinherited. The younger brother does fine but gets murdered before he can inherit, so the empire went to the Tsar's 4-year-old grandson. Factions broke that apart and he let himself shrink back to owning Crimea alone. Halychyna breaks away, the Byzantine and Arabian empires launch holy wars, their targets launch rebellions... yeah.
So, from Crimea, I create a new hybrid, combining the Halychnians and Khazars, and calls it the Crimean Tatars (Qirimtatar). Basically, it's the same as the Halychnians, but they speak Oghur Turkish instead of East Slavic and women can be commanders (And, like, thanks to reformed Taltosism, a Bellicose ethos, and dynastic traditions, all dynasty members get +8 Prowess for free, so yeah, let the women fight).
It was popular.