There was a supernova about 40,000 years ago, which notably killed off half of the life on the planet, a bright flash of X and Gamma rays from this nearby explosion.

Then, about 20-28k years later, debris that was shattered and set in motion by that explosion finally reached us, part of what we know now as the Taurid meteorite cluster, which is connected to several significant historical comet sightings.

This event was basically the pummeling of the region spanning across the americas and europe, over to the edge of the Black Sea, where there is known to be a whole bunch of large meteorite strikes scattered across the western pacific, on the northern american continent, the atlantic, europe, the mediterranean and north africa.

This event was the one the Great Flood story relates to. I am not sure if you know of the research associated with this, but there is some good evidence to suggest that Noah was probably living somewhere that is now Bulgaria, Romania or maybe Ukraine, that he lived inland, and when the meteorites struck, it punched the water of the black sea in a great tsunami inland up towards the Thracian Plain and the northern plains, where all kinds of hell would have been breaking loose, probably constanst rain from steaming seas, and such a boat, assuming it didn't get broken, could have then been dragged back towards the sea as it returned to the basin, and then back out through the Bosporus and they landed on a Greek island, where their dove found an olive leaf.

But in other parts of the world the survivors story was different. In some places there was airbursts, and only people who sought shelter in mud or shallow underground refuges, where the danger was fire and bright explosions, where it hit the atlantic, so much water was stirred up that it traveled at near the speed of sound towards the coast of Africa and Europe and I think there was a series of strikes in closer proximity to particularly northern africa, which contributed to the complete destruction of the previously lush forests covering the region. And then around 1200 years later, there was another incident, while during this period there was a nuclear winter on the whole planet, leading to starvation and droughts, that did not hit the ground so much as streak across the sky between china and the atlantic, over head of the north african continent, and the heat and radiation of this killed off what little life remained after the tsunami 1200 years before, and gave us what we have today, the Sahara.

Anyway, just re-telling my understanding of what I've been reading in The Apocalypse of Yajnavalkya. If you want to read it yourself, it has lots of references to texts and research and various other things that corroborate what it says.