Often called "the roof of the world" and sometimes "the crown of Azeroth", Northrend is a frozen wasteland that lies far to the north. As with the other continents, it was once part of the original Kalimdor landmass that was broken apart during the Sundering. The land that became Northrend drifted far from Azeroth's temperate zone, which killed off a large portion of the remaining wildlife.
Northrend also contains The Dragonblight: an enormous ice plain covered with the bones of thousands of dragons. As they near death, the great beasts fly to Northrend so that they may die with their ancestors. The blue dragonflight, led by the enigmatic Malygos, watches over the Dragonblight to ensure that the remains are undisturbed. The blue dragons were successful in their task for many thousands of years, until the coming of the Lich King…
The appearance of the Lich KingEdit
After Ner'zhul the shaman was captured and tortured by Kil'jaeden, the demonlord transformed the ancient Orc into a dark being of immense power. Now called the Lich King, Ner'zhul was imprisoned within a block of ice and cast back into Azeroth. Ner'zhul's prison landed at the base of the mighty Icecrown Glacier, by far the largest glacier in Azeroth. From this secret location, the Lich King used his telepathic powers to enslave many of the native life forms, including Ice Trolls and Wendigo. With these servants, Ner'zhul created a small army for himself. The Nerubians, aware of the Lich King's threat to themselves and the world at large, launched an attack on Ner'zhul's forces. Thus began the War of the Spider.
After ten long years of war, the nerubians were eventually defeated by the Lich King's endless supply of undead warriors and aid from the Legion's nathrezim. Most of the Nerubians were slain and reanimated as soldiers in the Undead army, while those who remained alive continued a guerrilla war against the lord of the dead. Satisfied that Northrend was his, Ner'zhul began consolidating his forces for the corruption of Lordaeron. To this end, the Scourge stole many sets of remains from the Dragonblight, which were then reborn as lethal Frost Wyrms.
By the end of the Third War, Northrend had seen the corruption of Prince Arthas, who had followed the nathrezim Mal'Ganis to the cold north in an attempt to stop the Scourge, as well as an invasion attempt by Illidan's Naga and blood elf forces, who had hoped to destroy Icecrown and the Lich King. This invasion was thwarted by Arthas and Anub'arak however, and Ner'zhul successfully merged with Arthas to free the Lich King from the Frozen Throne. The Lich King now holds complete domination over Northrend, and the living dare not tread on the frozen continent—especially after a disastrous invasion attempt of the Scarlet Crusade which ended in the expeditionary force being decimated.