Thank you Sanku-ji.
This is my theory {so no proofs or references}.
A great Tsunami/Asteroid type of cataclysmic event happened circa ~3000BC; which had a global impact. All the civilizations perished to the greater extent as most of them existed on river deltas. Only the mountain dwelling tribes survived.
All major knowledge centers and technologies too got destroyed in that event. This is similar to a modern nation/society losing all their technology/knowledge advances if all major urban/industrial etc centers are nuked.
After the event the original Abraham (or whoever that is) perceived it as God's punishment for all the ills of the society while extolling certain virtues. The rest of the society sees it as an acceptable philosophy and moves on with it. This is similar to INC claiming sekoolarism as the solution to Indian social/political evolution. Since it contains some virtues of pluralism, which are the essence of majority culture, it becomes an acceptable structure, even though key minority systems do not buy into that structure as it has fundamental differences with their belief systems. {No disrespect meant to anyone/thing}
SD knowledge survived this apocalypse because of its tradition of Vanaprastha/Samnyasa. The rishis lived away from the major civilization centers often in mountain regions (it is said that there are three Siddhabhoomis in Bharat - Himalayas, Srisailam, and Arunachalam; where Siddha purushas are doing penance even today in superhuman-dimensions). That is why SD maintained the memory of ancient knowledge today.
Assuming this, it is very much possible for Vedas to be the paramount knowledge for entire earth; as there are no abrahamic-type faiths at that point. Here Vedas being the knowledge repository that is life-style agnostic, and recommends reverence towards all forms of living/non-living being, and offers self-realization at individual level so on.
Here the sapta-samudras could be the sapta-matrukas {that represent Shakti in Siva-Sakti interplay} used to create the universe; Jambudwipa being the lowest 4D reality.
That Jambudwipa has all human/non-human civilizations as part of it. That is why Kubera could be a Hindu king/deity living in CAR/Russia region and so on. And Some maharshi might have his hermitage in Peru. That is the "Vasudhaika Kutumbam" and any enmity/fight is between individuals or dharmas and not between civilizations?
While people cannot believe the possibility of wars involving 3-4 million armies circa 3000BC, there are few standing archeological sites (Pyramids, Angotkarvat, Mayan pyramids etc) which are individual projects requiring tens of thousands of workers working on a single site/project. Compare this with a reliance refinery of 10-20,000 employees and India's standing army of 1+ million and another 2+ million paramilitary+CRPF+Police etc forces. Mahabharat war involves most of the Eurasia region and 3-4 million total army is not that unimaginable.
On the cyclical concept of time - I came across this paper ~4-5 years ago. My laptop-harddisk crashed two days ago
(talk about coincidence). I am actively searching for it and will post it as soon as I find it. In that paper that archeologist had pictures of various artifacts dating millions of years and he talks about the layers of archeological findings. In one example he talks about a finding of two artifacts where one dated ~2-3000BC where as the other one showed Million+ year in carbon dating. He says people took the 2-3000BC date calling the second test as some aberration.
And I noticed the same approach in the astronomical book I mentioned above. The author dates a specific mention of astronomical event in Aitereya Brahmana to be either 1500BC or 15000BC (Some Ashada Suddha Padyami being the Ugadi=new year day or something like that) and takes the 1500BC date because 15000BC is not feasible without giving any reason/logic.
The starting of lunar year changes 1 day for every <1 degree movement in earth's precision-of-equinox that takes nearly 70 years (~26000 years / 360 degrees). So the tidhi mentioned in lunar calender repeats every so often.
... Just some random thoughts.