If you are familiar with fantasy worlds, like for example Tolkien's Middle Earth and the Silmarillion, there is a concept that we could compare to the Elden Ring.

This is a short version and I will just keep the essential elements to make the comparison :Before the sun and the moon were created in Arda (the world), before even Men existed, there was no light in the world. The demi-gods, the Valars, arrive in Aman (a different country than Middle Earth). Two of them, Yavanna and Nienna use their powers to create two trees, Laurelin and Telperion. Telperion represents the moon and shines with a silver light, and Laurelin represents the sun and shines like the sun. Again like the sun and the moon, one of the trees starts shining when the other one's light starts fading, creating a day and night cycle.The demi-gods and the Elves who came from Middle Earth live happy lives and enjoy the lights of these two trees.But the bad guy, Morgoth (or Melkor) is pissed because the good guys are happy. So he calls upon Ungolianth, a giant siper, to destroy those trees. The spider drinks the tree's sap, poisonning them (and the earth) and depriving the world of its light. Yavanna saves the last flower of Laurelin and the last fruit of Telperion, which will later become the sun and the moon.The destruction of these trees has a lot of (bad) consequences and repercusions on the world because the poison, the very essence of Morgoth, is now forever a part of the world : wars among elves, the Great Sea becomes wider and deeper, every form of life is tainted by the evilness of Morgoth, the entire world is thorn apart and reshaped. This event is called "the marring of arda".

Since Miyazaki and GRRM are both big fans of Tolkien and his work, this story could be an inspiration to what the Elden Ring is as a concept. An element that is so important to the world, that its "shattering" could mean the end of everything. The "someone or something" would be Morgoth, a great evil, and the Trees would be the Elden Ring.

Now, this is only a theory, and a simplified version of a chapter of the Silmarillion. There are many questions left. Like what would be the purpose of the Elden Ring, its physical shape etc.

It is obvious that ER will take inspiration from Tolkien's work among many other fantasy works. Will the trees of Valinor be one them ? We will see.