Maybe I am late to the party, though I don't remember anybody specifically mentioning re-reading the beginning of the Tobi story arc after Held and friends shifted to this realm...

Now beginning of Tobi's story reads exactly like if king Baku and others did carve out their kingdom in the spirit realm and created their city in some distance from their pyramid. This factory could be another such city, just placed in a different biome (I'd say one far harder to traverse than a flat-ish desert).

"fled through the cracks" Yes, yes, just continue - how did they accomplish that?

Maybe this is a postapocalyptic world, and they find whatever you normally find there (like mutants and monsters).

It would certainly count as a "knowledge", though how useful, it remains to be seen. I mean, what do you do with knowledge that you will be devoured in the next few seconds, for example?

The cracks eh? And just what sort of cracks were these?