I've had this really weird idea in my head for awhile now. It's Alien Space Bats; and really strange. Heres the description:
A virus breaks out in Africa that wipes out the Human population on the vast majority of the Continent, and mutates some of the animal species into; well, Furrys. In other Words; Cat people now walk the earth, along with Wild Dog and Jackal people. Ok, heres where things get strange; instead of the Moors; it's the Panther people who invade Visigothic Spain and take it over. This leads to people scratching their heads all over Europe and the Middle East. However; when the Pope declares the third crusade to reclaim the Iberian Penninsula, during the 1100's; the Panther Men invade and conquer France. However; the Britons and Brittaney fight on and push the Panthers out of Britanney. Brittany manages to reclaim some ground while the Muslims and Christians duke it out in Italy and Rome ignoring the Panther people. In the end, the Britons reconquer Normany; and essentially become this worlds France... Well; Northern France.
Does this weird idea count?
As for a really realistic scenario; I suggest checking some of Harry Turtledoves novels. Sure, the Sex Scenes are horrendous, but some of his idea are quite cool in my opinion. Like, 1812; where a Indian State exists.