Level design?

Hello folks.

I’ve been playing many MMORPG’s, completely created in the UE and I’m wondering how the producers where able to create such a huge world while the Unreal Engine is not that big for such a huge map to be able to create.
I’m talking about games like Blade & Soul for example which map is really big and I can’t imagine they built it up just in only single map. Did they build a new instance for any area or something simular? I’m pretty new to the Unreal Engine so would be appreciated to teach or explain gently :slight_smile:

Thank you very much.

Best regards,