It's not any "medieval Poland", it's another world altogether with people and creatures from different worlds and most have Germanic and/or Celtic names.
Ciri (Greek name) in the books repeatedly visits ours world (Earth) in various places and eras, and I don't think it's Poland even there (unless the German owned Prussia counts), instead she goes to France and so on. It ends with her in King Arthur's Camelot.
It's not any "medieval Poland", it's another world altogether with people and creatures from different worlds and most have Germanic and/or Celtic names.
Ciri (Greek name) in the books repeatedly visits ours world (Earth) in various places and eras, and I don't think it's Poland even there (unless the German owned Prussia counts), instead she goes to France and so on. It ends with her in King Arthur's Camelot.