Marx makes it very clear that he never believed in "Golden Past of India."
So, you get it where Marxist Historians have based their notions from.

4/n Then Karl Marx goes on to humiliate Hindu beliefs of worshiping Hanuman, Cow & nature.
— Aabhas Maldahiyar \U0001f1ee\U0001f1f3 (@Aabhas24) May 6, 2021
He hints that how British were eradicating these beliefs.
The great philosopher, Marx was so blinded by faith of Man being supreme, could not understand depth of nature worshiping. pic.twitter.com/ul7NlxxwF0
Old is Gold....
— Professor (@DillikiBiili) January 23, 2020
this Bharti Airtel chart is a true copy of the Wyckoff Pattern propounded in 1931....... pic.twitter.com/tQ1PNebq7d