From the Emmy Award winning HBO series, Game of Thrones, based on the novels by George R. R. Martins book series, "A Song of Ice and Fire." The North is the largest of the Seven Kingdoms of Westeros and it was an independent kingdom for 10,000 or more years before Torrhen Stark bent the knee to Aegon I Targaryen. Torrhen was named Warden of the North for his swearing fealty to Aegon I.
After Robert's Rebellion and subsequent victory, Robert Baratheon was crowned King of the Seven Kingdoms. He later succumbed to a hunting injury and died, leaving two brothers, Stannis and Renly, and his "son" Joffrey to vie for the crown. After Joffrey executed Ned Stark for "treason," Robb's bannermen declare him the "King in the North."
Robb is betrayed by the Freys and is killed at The Red Wedding by the Lannisters, Boltons and Freys. With Bran and Rickon presumably dead, House Stark has no male heir. Sansa is a captive of the Lannisters at King's Landing while Arya is presumed dead.
Jon Snow is at Castle Black as a member of The Nights' Watch and is ultimately elected as the 998th Lord Commander of The Nights' Watch before being killed in a mutiny led by Ser Alliser Thorne and Bowen Marsh. After being resurrected Melissandre, Jon is freed from his oath to The Nights' Watch as death frees a member of the Watch from their duties.
He learns that Ramsay Bolton has Rickon Stark captive at Winterfell and he summons the remaining Free Folk to follow him to take back Winterfell because only a united North can stand any hope of defeating The Night King and the army of the undead. After defeating Ramsay with the help of Sansa's efforts to enlist the aid of the Knights of the Vale, Jon is made King of the North as the Northmen prepare for the upcoming storm.
After the combined forces of Jon and Danerys Targaryen defeat Cersei Lannister and retake the Iron Throne, Jon reluctantly kills Dany because she has become tyrannical and bent on world domination. As there is no rightful ruler of the Seven Kingdoms, Tyrion suggests that the most powerful lords and ladies of the Realm choose and new ruler and from this day forward, all future rulers will be chosen by a council of the most powerful in the Realm instead of by birthright. Bran Stark is chose by the council to be "king" but he grants the North its independence after Sansa declares that too many northerners died protecting all of Westeros to ever bend the knee again. Sansa is then crowned the "Queen in the North."