Genshin Impact has excellent world-building, with stories that have happened as far back as thousands of years ago--stories like the Archon War. Genshin Impact's Archon War was a means of deciding who would sit in the seven seats high above in Celestia and become an Archon. Not every god had an interest in that; some just wanted to defend their territory. Once the gods had their seats, the nations of Teyvat were divided up and given to the gods. The land was there before, as the gods were already in their regions, but now it was more official, so to speak.