The latest trailer for Pokémon Legends: Arceus featured some strange dialogue that hints that Arceus was once referred to as Sinnoh, which would later become the name for the Hisui region. Pokémon Legends: Arceus is set in Hisui, which is the ancient name for the Sinnoh region from Pokémon Diamond and Pearl.
It's unclear when the name of the region changed, but many fans assume that it will happen at the end of Pokémon Legends: Arceus, possibly at a moment when humans and wild Pokémon start
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