Reading the "http://www.uesp.net/wiki/Lore:Battle_of_Sancre_Tor", the location of Falkreath makes no sense if we go by the Skyrim location, given that this is the Colovian kingdom Tiber Septim fought for at the time. As the Nord-Breton forces moved into the highlands and occupied the paths through the Jeralls, how could Talos have attacked Sancre Tor from the other side of the Jeralls?

My hypothesis for this is that the (now apparently gone)Colovian kingdom of Falkreath and the Skyrim Hold of Falkreath are separate locations, perhaps ruled the Jarl of Falkreath at the time of the Skyrim Conquests or perhaps during the Alessian Order, as Alessia supposedly granted land to Nordic warbands willing to fight for her. The fate of this Colovian Falkreath could be that it was assimilated into Chorrol or Bruma County with the death of Emperor Zero.

Just some thoughts I had.