See, some people do alt history to genuinely find an interesting new take on historical divergence points, some use it to play out their weird geopolitical fantasies. Me? I throw a big rock at the planet and then delight in putting the pieces back together, can’t recommend the “throw a big rock at it” method enough.
tired, boring, played out, done to death: but what if the Nazis had won the war?
exciting, fresh, abjectly insane, affects more than half of the common era: but what if Charlemagne had decided against ultimogeniture and not split his european conquests between his sons?
hell, let's take it a step further: what if the roman empire just never fuckin' happened. the entire cultural fundament of the modern day west, just fwoosh gone. christianity remained its own little thing out in the middle east, the roman republic never grew beyond its initial borders, just yet another city state of the same kind you had oodles of in greece. no migration period, though the vikings would probably have still done their thing and made their largely unsuccessful ventures to north america.
how would that even play out over two thousand years later
Further still: What if the Strait of Gibraltar never opened? The Mediterranean remains a series of salt flats and saline lakes fed by southern Europe's rivers, curtailing the development of civilisations at its coasts due to the lower access to food and maritime trading.