What if the Soviets had a significant obsession with ideologically motivated pseudo-archaeology, much like the Anatoly Femenko's "New Chronology", the Nazi Ahnenerbe and Thule cult, or Olof Ohmans "Kensington Runestone"?
As for the POD, maybe Stalin is just obsessed with pseudo-archaeology and occultism and through him, a cult is created. Producing "evidence" for pseudo-historical ideas that the Soviet bureaucracy finds useful or just really want to believe.
Soviet Pseudo-Archaeology and Occultism could be focused on finding (manufacturing hoaxes, or modifying existing artifacts to produce a hoax) evidence and artifacts that "prove" the existence of an Atlantis civilization in Ukraine or the Caucasus, that key historical figures were proto-communists, that the medieval Slavic lands were hyper-advanced for the time or the Russian Empire was the first civilization, that Slavs created the Roman Empire, that Scythians, ancient China, or Mongols had been Slavs, that the Vikings or Kievan Rus were an egalitarian communist society destroyed by Bourgeois Crusaders, that Greco-Roman gods were derived from pagan Slavic gods, that human species evolved on the Volga, or finding "prophecies" of world revolution from ancient times.