So... I’m (finaly) reading AWoIaF and this part got my attentation:
Song and story tell us that the Starks of Winterfell have ruled large portions of the lands beyond the Neck for eight thousand years, styling themselves the Kings of Winter (the more ancient usage) and (in more recent centuries) the Kings in the North. ...
ch. The Kings of Winter
The Kings of Winter
King of Winter
...
Catelyn was thinking of her girls, wondering if she would ever see them again, when the Greatjon lurched to his feet. “MY LORDS!” he shouted, his voice booming off the rafters. “Here is what I say to these two kings!” He spat. “ Renly Baratheon is nothing to me, nor Stannis neither. Why should they rule over me and mine, from some flowery seat in Highgarden or Dorne? What do they know of the Wall or the wolfswood or the barrows of the First Men? Even their gods are wrong. The Others take the Lannisters too, I’ve had a bellyful of them.” He reached back over his shoulder and drew his immense two-handed greatsword. “Why shouldn’t we rule ourselves again? It was the dragons we married, and the dragons are all dead!” He pointed at Robb with the blade. “There sits the only king I mean to bow my knee to, m’lords,” he thundered. “The King in the North!” And he knelt, and laid his sword at her son’s feet. “I’ll have peace on those terms,” Lord Karstark said. “They can keep their red castle and their iron chair as well.” He eased his longsword from its scabbard. “The King in the North!” he said, kneeling beside the Greatjon. Maege Mormont stood. “The King of Winter!” she declared, and laid her spiked mace beside the swords. And the river lords were rising too, Blackwood and Bracken and Mallister, houses who had never been ruled from Winterfell, yet Catelyn watched them rise and draw their blades, bending their knees and shouting the old words that had not been heard in the realm for more than three hundred years, since Aegon the Dragon had come to make the Seven Kingdoms one . . . yet now were heard again, ringing from the timbers of her father’s hall: “The King in the North!” “The King in the North!” “THE KING IN THE NORTH!”
She isn't just proclaiming Robb her king, she's acknowledging eight thousand years of history with one simple phrase.