Quote Originally Posted by Kotrag View Post
That's part of the Chronicle of Nurn Shieldbreaker and details the tribes who came through the Blackfire Pass. I'm talking about the Chronicle by Dread Yngvar Iovarsson, which states that the Norsii, Ungol, Friking, and Roppsmenn migration predates the Blackfire Pass migration by 20 years.
I think it applies to both chronicles:

"Such small contradictions are common when one studies these early times. The only certain thing is that approximately 1000 years before the birth of Holy Sigmar, tribes of Humans migrated to, or were driven into, the Reik Basin.
Most fled the lands from across the World Edge Mountains, although it seems likely some also came from the Badlands.
" (emphasis mine)

Nowhere does it state any of the tribes came from the north.
Much like in the real world, civilisation started in the warm climates of the south in the Warhammer World.
Even before the collapse of the Chaos gates the poles were harsh and inhospitable lands so I doubt a tribe of humans could have evolved there.

Quote Originally Posted by Kotrag View Post
I don't know about the Norsii being related to the Kurgan. Modern Norscans and Kurgan have probably mixed, due to mutual raiding, trade networks, intermarriages, etc., but the description of how the Norsii and Kurgan encountered each other in the Legend of Sigmar novel made it seem as if the two had very little prior contact before the Norsii founded Norsca.
True, though due to lack of a standardised background document many novels (accidentally) retcon established history form other sources.
Look at what happened to the Liber Necrics and the Von Carstein trilogy for example.