Board Thread:Lore Discussion/@comment-3573184-20131017160735

So, in my boredom, I decided to map all the locations that Falmer appear in Skyrim, and I found a surprisingly accurate spread of Falmer, based off of where lore says they should be.

As seen on the map here: http://i1142.photobucket.com/albums/n619/TheSajuukKhar/falmermap_zps0fb3a803.jpg
 * The highest concentration of Falmer locations is in The Pale and Winterhold.
 * As "Songs of the Return" states, the Falmer did not settle the Whiterun plains, in fear of the skyforge.
 * The Falmer don't appear in Falkreath at all, which seems reasonable given how they feared Whiterun.
 * The Falmer only appear in the very south-eastern part of Eastmarch, and only just barely in the most north-eastern part of Riften, in three Dwemer ruins, just as Skorm Snow-Stirder's Journal states that he wast sent to the most southern parts of Nord lands to drive some Falmer north, and that the closer they got to Lake Honrich, the less they saw of the Falmer.
 * Guards say that the troubles on the road(near Chillwind Depths) are a recent thing, and the Falmer's incursion into Liar's Retreat is most likely from the nearby Chillwind Depths tunnels.
 * The Falmer's presence in the Gloomreach, in the southern Reach, is likely a result of spreading from the Dwarven ruin Arkngthamz(although this requires some reverse logic here as that ruin is a DLC location, while the cave isn't.)
 * And, as admitted by Gelebor himself, Darkfall Cave, aka the entrance to The Chantry of Auri-El, was a remote place. Very remote seemingly.

In conclusion, the in-game presentation of the Falmer's nests is seemingly consistent with where the lore says the Falmer lived. With the few exceptions of some Dwemer ruins, places they likely fled to, or were brought to after their enslavement.

The only places I can't really reason are Haafingar's Lost Echo Cave, and Darkwater Pass in southern Eastmarch, but there's always exceptions, and "recent spreading" is a likely culprit. 