Canyon of Corruption

I'm saying this because you might not know about it. I have this question stuck in my head and I can't get rid of it. For a while, the northwestern area of Mediah was called Rumbling Land. Did you know that? There were many big and small areas. But people these days call the eastern part of Rumbling Land the Canyon of Corruption. I was just wondering why it has a name like that. Do you know about this?

Canyon of Corruption... It's really awkward. I wonder since when and why people are calling the Eastern Rumbling Land by that name.

I heard Cultists have taken over the monastery, but I didn't know they worshipped evil gods of corruption. The damage must be huge since the region has that kind of name. The great Chief Tantu won't just sit and watch this kind of shameful event.