The Shadow Isles: before the fall.
There are a few hints at the nature of the Shadow Isles pre-undeath. Maokai was a forest spirit and the land teemed with both animals and spirits. There was a sacred forest. Hecarim is a centaur, which could imply he was a nature-creature before undeath. A spider-themed god remain there: maybe there were other animal gods as well. There was a kingdom and a Ruined King.
I interpret this to suggest roots from one part nature-themed and one part Shakesperian/Arthurian legend, the latter parts considering the champions who reside there now.
Any thoughts?
this Ruined King's weapon?