The history of the Doomsday Party undoubtedly filled the gaps in Marvin's understanding of the Era of the Divine Tree.
If merely listening to one side of the Doomsday Party isn't enough to confirm the truth, then beneath London, the Alchemy God Tree etched upon the altar of the Golden Age Lundinium Ruins shall serve as irrefutable evidence.
The Alchemy God Tree was created by the Ancient God Ashis. At the end of the Ancient Gods Era, she suddenly ascended to land, defeated the Covenant Ancient God and the Ancient God of Wisdom, causing the Land of Death and the real world to separate, which is what the Doomsday Party referred to as the world being split into two.
In order to connect the separated worlds, Ashis planted the Alchemy God Tree, linking the two worlds together, and at the same time, the exhausted Ashis fell into a deep slumber.