Ok, I was just going to go with generic north tribesman but here goes nothing. Keep in mind, all of this I am making up.
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Located on the small patch of viable land in the north, there is little known of the Northern Tribes. For the most part they are very isolationist with little to no contact with the outside world. However that doesn't mean that they are all savage, primitive people. While that is true for the majority of the smaller tribes, the four biggest ones are on par with many cities.

The home of Angron, Khorne. The tribe is the farthest to the north, laying inside a great glacier. How the Bronze City came to be is a mystery lost to time as none within its halls care for such trivial matters. The people of Khorne are warriors, raiders, and soldiers renowned for their great strength and size. With the average male being 6'3. However living inside the ice does not bode well for agriculture and as such much of the food is taken from the tribes of the south. 

Their god, Kharn, is a god of blood, skulls, and honorable combat. When a warriors dies in the fires of battle, than his soul is taken to the Halls of Kharn where he will feast, tell tales of battle, and fight in the Ash Pits with his fellow warriors. Holy symbols are Axes, blood, and bronze.

Many would assume that tribes of the north are stupid, wild beings that are not worth much attention. However, many are surprised to find that they are capable of making wonderous and often time deadly creations. Like the Maze of Tzeentch, the Plague Forests of Nurgle, the Palace of Pleasure dedicated to the pleasure god Fulgrim, or even the Bronze City. When the North men put their minds to something, there is very few beings that can stop them. Thankfully they seem content to fight each other in petty wars.