U. of Bremen prof. emeritus Dr. Gunnar Heinsohn finds evidence of a cometary catastrophe causing a wave of destruction in the Mediterranean around 300AD which spelled the end of the Roman Empire and left humanity in a dark age that only recovered during the Enlightenment which kicked off the Industrial Revolution.
https://www.youtube.com/watch?v=hYuG8iFEVrc
Gunnar Heinsohn also thinks the Harappan civilization is thousands of years younger and actually the remains of post-Alexandrian Hellenistic kingdoms.
“Gunnar Heinsohn holds a university diploma in sociology (1971) and doctorates in the social sciences (1973) and in economics (1982).”