Well, I don't know if there's a TL about it, but the biggest POD I can think of would be the Toba Supervolcano Eruption. Not by changing the Eruption itself- obviously, a geological POD like that would be ASB by default- but simply by having different groups of survivors. IOTL, it's believed that the Toba super-eruption caused a huge genetic bottleneck, and that all of humanity is descended from those 1000>10000 individuals who survived the cataclysm. If some tribes make worse decisions during the 6>10 yr post-apocalyptic volcanic winter which ensued, which eventually result in their tribal lineages dying out entirely- and conversely, if other tribes make better decisions during that period, and end up being the ones who survive to repopulate the earth instead- then you'd have a completely different human race, with different cradles of civilisation, different migrational paths, different cultures, different nations (if the conept even arises ITTL) and a completely unrecognisable Earth.