Zero-point energy weapons.
Created from baked clay and sticks.
Shows what you know! Clearly the ancient civilizations lived in mobile homes.
Of course, then you have to be open to the possibility that instead of nuclear weapons, the civilizations were destroyed by giant tornadoes.
Once while browsing through a Hare Kṛṣṇa book, I noticed a reference to a “nuclear bomb” used in an account of those ancient Indian wars. Naturally incredulous, I perused it for any possible explanation. Turns out that the “nuclear bomb” was actually a mantra. A magic incantation. The editor of that text seemed to believe that a mantra could wreak the devastation of a nuclear weapon, and that calling it a “nuclear bomb” was metaphorical.
Hey, I just hit 5 figures! 10,000 posts! Buy me a drink! 
Perhaps a nice bhang lassi, given the thread topic.
I suspect time travelers duking it out.
What talk of nuclear weapons 4500 years ago and no mention of ancient aliens? I mean, c’mon, that covers everything. They used nukes or some similar technology to eradicate old civilizations, then used their advanced technology to clean up the radiation, then did their genetic engineering and were worshipped as gods. After all, there’s not any evidence that aliens didn’t do it. Just ask Giorgio Tsoukalos.
Science introduces the concept of ancient mass irridation. And then someone leaps on it …for whatever reason.
'*Our research indicates that the entire Great Lakes region (and beyond) was subjected to particle bombardment and a catastrophic nuclear irradiation that produced secondary thermal neutrons from cosmic ray interactions.
*
The neutrons produced unusually large quantities of 239 Pu and substantially altered the natural uranium abundance ratios (235 U/238 U) in artifacts and in other exposed materials including cherts, sediments, and the entire landscape.*
These neutrons necessarily transmuted residual nitrogen (14 N) in the dated charcoals to radiocarbon, thus explaining anomalous dates."
Richard B. Firestone
Granted Firestone makes no mention of ancient nuclear war, he describes particle bombardment—wherever it came from.
Then in news from the other side of the world we have ancient Sanskrit articles. The Vimanas, that describe flying machines, and weapons of mass destruction. At least they have been translated that way. Egypt too, provides its share of hieroglyphics that portray flying machines.
You also neglect to mention that the events Firestone is discussing occurred 41000-13000 years ago. So no connection at all with ancient Sanskrit scripts or Egyptian hieroglyphics.
I’m skeptical about some of Firestone’s conclusions - I doubt that iron-rich grains of material from a supernova would penetrate the atmosphere and still hit a mammoths’ tusk at 10000 km/s. But the nuclear science looks pretty good and the risks of a gamma burst/supernova on the earth have been studied.
I wonder how we would cope today with a supernova in the neighbourhood. Fortunately, we will not find out, as our local stars seem stable enough (Beleguese is likely to supernova at some stage, but is too far away).
Si
Even if they had a sufficient quantity of coconuts provided by teams of African Swallows working in pairs grasping them by the husk?
Yeah, probably. By people looking for radioactive elements and by scientists looking for evidence of nuclear testing. Also, just for purposes of basic science. Consider the iridium anomaly.. Pretty sure that a nuclear event big enough to wipe out civilizations with no trace would leave noticeable traces in the geologic record.
And mineshafts; we couldn’t have had fission bombs without uranium mines.
A civilisation that blew itself up 10,000 years ago would have almost completely disappeared above ground, but any substantial excavations of any kind would be almost all intact after such a geologically short period.
Hmm… So the Money Pit on Oak Island was really an ancient uranium mine.
See?! The ancients used up all the uranium that was just lying around in surface-rocks, that’s why we have to mine it today, QED.