Ancient ruins that predate the White Lords. Indications that the White Lords were not the first intelligent mice to live in the Fallows, but that some ancient empire predated them... then fell into decay and eventually all returned to mindless barbarism. Heh... maybe they should have been guinea pigs...
I still need a name/hook for the big, rich, crime-ridden capital city where all urban adventures generally occur. Samsara on RPG.net suggested Haven, which I kind of like.
The crime network is the Gleaners... a nice, innocuous term for folks who snatch up a little bit of everything. The Black Paw is a mysterious group of assassins associated with the Gleaners... their mark is a paw-print of black paint on the face of a dead victim. Thanks to Samsara again for both of those names.
I might use Jakatas for the name of the ancient ruins (another name from Samsara, along with Tsarchul, which I don't have a use for yet. It could be the name for those mysterious inhabitants, though: "The Tsarchul".