Sure, sure. Eric mentions that the jungles of Klatch are full of ruins, e.g. lost kingdoms full of Amazonian princesses (which we never see).
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Lost gold mines (which, again, we don't see).
We
do meet the Great Muzuma (briefly), but he (she?) is not an Amazonian princess.
As for Klatch: I wouldn't take "Eric" as canon, personally. I think it was "filler", just to get Rincewind out of the Dungeon Dimensions. It's a tasty filler, and amusing, but it doesn't really help to 'build' the Discworld.
To build the Discworld, I would rely more on
"The Discworld Atlas.