They were once their own kingdom, separate from the Iron Throne's rule, but the last King in the North, Torrhen Stark, bent the knee to Aegon the Conqueror, who would have decimated Torrhen's people in battle with his dragons. At the beginning of the War of the Five Kings, Robb Stark was proclaimed King in the North and vowed vengeance for his father's death at the hand of Joffrey Baratheon.