Your mission, should you choose to accept it, is to pick a scenario where at least two, much better three, multi-national and basically territorially-continous centralized Christian empires form in the High-Low Middle Ages or the Early Modern Age in Europe, stay together up to modern times, colonize the world at least as extensively as UK/France/Spain did in the Age of Exploration, and turn the rest of Europe and the Middle East in their centuries-long disunited warring ground. PoD is after Charlemagne's death. The empires must stretch at least a couple of big modern nation-states (say any two of Britain/British Isles, pre-1550 France, Greater Germany, Italy, Spain/Iberia, pre-1918 Hungary, pre-partition Poland, Scandinavia). Brownie points if it reverses the fortunes of at least a couple areas that in OTL unified early, late, or never at all.