Yeah, with all the screenshots of the river in Oddworld 4, it could potentially take place on the river that Abe and Munch ended up near at the end of Munch's Oddysee, which would make it easier for the effects of this game to be felt in the Quintology, which would make sense in the 'running concurrent with the evolution of' phrase.
However, that would place it far away from both Necrum and Scrabania. And SS, it's difficult to tell with that map, but I'm pretty sure that the bottom of your two question marks is actually outside the boundaries of Mudos - if Mudos is the highlighted green land, it is, at least.
|