Board Thread:Lore Discussion/@comment-24597741-20140106210548/@comment-4705438-20140107031300

Humans reproduce much faster, take up lands and expand. What might have been a trading outpost once might turn into a city in time it takes for a snow elf to reach maturity.

Falmer were becoming outnumbered in their own lands. This, no doubt, spread fear and hate towards the Atmorans.

And then there's the Eye of Magnus. A powerful artifact that would only multiply the previous negative effects.

It's really all explained in the Falmer-Nord War page, if I'm not mistaken.